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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">ETM</journal-id>
<journal-title-group>
<journal-title>Experimental and Therapeutic Medicine</journal-title>
</journal-title-group>
<issn pub-type="ppub">1792-0981</issn>
<issn pub-type="epub">1792-1015</issn>
<publisher>
<publisher-name>D.A. Spandidos</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="publisher-id">ETM-25-4-11857</article-id>
<article-id pub-id-type="doi">10.3892/etm.2023.11857</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Articles</subject>
</subj-group>
</article-categories>
<title-group>
<article-title><italic>IFITM3</italic> rs12252 polymorphism and coronavirus disease 2019 severity: A meta‑analysis</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name><surname>Yu</surname><given-names>Kai</given-names></name>
<xref rid="af1-ETM-25-4-11857" ref-type="aff">1</xref>
<xref rid="fn1-ETM-25-4-11857" ref-type="author-notes">&#x002A;</xref>
</contrib>
<contrib contrib-type="author">
<name><surname>Wang</surname><given-names>Jingjing</given-names></name>
<xref rid="af2-ETM-25-4-11857" ref-type="aff">2</xref>
<xref rid="fn1-ETM-25-4-11857" ref-type="author-notes">&#x002A;</xref>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Li</surname><given-names>Haibin</given-names></name>
<xref rid="af1-ETM-25-4-11857" ref-type="aff">1</xref>
<xref rid="c1-ETM-25-4-11857" ref-type="corresp"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Wang</surname><given-names>Wenjun</given-names></name>
<xref rid="af3-ETM-25-4-11857" ref-type="aff">3</xref>
<xref rid="c1-ETM-25-4-11857" ref-type="corresp"/>
</contrib>
</contrib-group>
<aff id="af1-ETM-25-4-11857"><label>1</label>Department of Surgery, Affiliated Hospital of Beihua University, Jilin, Jilin 132011, P.R. China</aff>
<aff id="af2-ETM-25-4-11857"><label>2</label>Department of Pediatrics, The Second Affiliated Hospital of Xi&#x0027;an Jiaotong University, Xi&#x0027;an, Shaanxi 710004, P.R. China</aff>
<aff id="af3-ETM-25-4-11857"><label>3</label>Department of Infectious Diseases, The Second Affiliated Hospital of Xi&#x0027;an Jiaotong University, Xi&#x0027;an, Shaanxi 710004, P.R. China</aff>
<author-notes>
<corresp id="c1-ETM-25-4-11857"><italic>Correspondence to:</italic> Professor Haibin Li, Department of Surgery, Affiliated Hospital of Beihua University, 12 Jiefang Middle Road, Jilin, Jilin 132011, P.R. China <email>1546726934@qq.com wenjun_wang@xjtu.edu.cn </email></corresp>
<fn><p>Dr Wenjun Wang, Department of Infectious Diseases, The Second Affiliated Hospital of Xi&#x0027;an Jiaotong University, 157 Xiwu Road, Xi&#x0027;an, Shaanxi 710004, P.R. China <email>wenjun_wang@xjtu.edu.cn</email></p></fn>
<fn id="fn1-ETM-25-4-11857"><p><sup>&#x002A;</sup>Contributed equally</p></fn>
</author-notes>
<pub-date pub-type="collection">
<month>04</month>
<year>2023</year></pub-date>
<pub-date pub-type="epub">
<day>21</day>
<month>02</month>
<year>2023</year></pub-date>
<volume>25</volume>
<issue>4</issue>
<elocation-id>158</elocation-id>
<history>
<date date-type="received">
<day>20</day>
<month>07</month>
<year>2022</year>
</date>
<date date-type="accepted">
<day>26</day>
<month>01</month>
<year>2023</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x00A9; 2020, Spandidos Publications</copyright-statement>
<copyright-year>2020</copyright-year>
</permissions>
<abstract>
<p>Interferon-induced transmembrane protein 3 (IFITM3) serves a critical role in the immune defense against viral infection, including that of severe acute respiratory syndrome coronavirus 2. To the best of our knowledge, the association between <italic>IFITM3</italic> rs12252 polymorphism and coronavirus disease 2019 (COVID-19) severity has not been determined. In the present study, a meta-analysis of published case-control studies assessing the association between the <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity was performed. PubMed, EMBASE, China National Knowledge Infrastructure, Wanfang and preprint servers were searched up to March 30, 2022. A fixed-effect model was used to calculate odds ratio (OR) and 95&#x0025; confidence interval (95&#x0025; CI). Analyses were conducted for additive, dominant and recessive genetic models. A total of five studies were identified, with 1,443 mild-to-moderate cases and 667 severe cases, including 121 deaths. Overall, the CC genotype of <italic>IFITM3</italic> rs12252 was associated with increased risk of severe COVID-19 (OR=1.97, 95&#x0025; CI, 1.06-3.69) and mortality (OR=4.61, 95&#x0025; CI, 1.44-14.75) compared with the CT/TT genotypes. Stratified analysis by ethnicity revealed that this association was strong in Chinese individuals (severity, OR=2.84, 95&#x0025; CI, 1.34-6.04; mortality, OR=7.91, 95&#x0025; CI, 1.29-48.44), but not notable in Caucasians (severity, OR=0.79, 95&#x0025; CI, 0.23-2.80; mortality, OR=2.16, 95&#x0025; CI, 0.37-12.55). A significant association with mortality was observed in Caucasians when comparing patients with the C allele of <italic>IFITM3</italic> rs12252 and those without (CC/CT vs. TT: OR=1.73, 95&#x0025; CI, 1.09-2.75). The results suggested that the <italic>IFTM3</italic>-rs12252 CC genotype is associated with severe COVID-19 and mortality in Chinese individuals and the <italic>IFTM3</italic>-rs12252 C allele may be associated with COVID-19 mortality in Caucasians. Large-scale studies are needed to confirm the association in different global populations.</p>
</abstract>
<kwd-group>
<kwd>coronavirus disease 2019</kwd>
<kwd>severe acute respiratory syndrome coronavirus 2</kwd>
<kwd>interferon-induced transmembrane protein 3</kwd>
<kwd>genotype</kwd>
<kwd>polymorphism</kwd>
<kwd>meta-analysis</kwd>
</kwd-group>
<funding-group>
<funding-statement><bold>Funding:</bold> No funding was received.</funding-statement>
</funding-group>
</article-meta>
</front>
<body>
<sec sec-type="intro">
<title>Introduction</title>
<p>Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a major health threat all over the world. As of 8 April 2022, a cumulative total of 494,587,638 COVID-19 cases were reported globally, including 6,170,283 deaths, according to the World Health Organization (<xref rid="b1-ETM-25-4-11857" ref-type="bibr">1</xref>).</p>
<p>The spectrum of SARS-CoV-2 infection ranges from asymptomatic to clinical symptoms, including fever, dry cough, dyspnea, fatigue, muscle pain, headache, diarrhea, loss of taste and/or smell, nasal obstruction and runny nose (<xref rid="b2-ETM-25-4-11857" ref-type="bibr">2</xref>). The majority of patients with COVID-19 have a mild or moderate form. However, infection in certain patients becomes severe, presenting with respiratory failure. In the most severe cases, acute respiratory distress and multiple organ dysfunction syndrome, coagulation abnormalities and shock have been observed (<xref rid="b2-ETM-25-4-11857" ref-type="bibr">2</xref>).</p>
<p>Older age (&#x003E;60 years), unvaccinated, associated comorbidities (such as cardiovascular disease, hypertension, chronic pulmonary disease, diabetes, chronic liver and kidney disease and malignancy), immunodeficiency, obesity and heavy smoking are key host risk factors for severe COVID-19(<xref rid="b2-ETM-25-4-11857" ref-type="bibr">2</xref>). Apart from these factors, studies have shown that host genetics may also be key in the development of severe COVID-19 and should be considered in COVID-19 prognosis (<xref rid="b3-ETM-25-4-11857" ref-type="bibr">3</xref>,<xref rid="b4-ETM-25-4-11857" ref-type="bibr">4</xref>).</p>
<p>Interferon-induced transmembrane proteins (IFITM1, 2 and 3) are stimulated by interferon and serve a critical role in the immune defense against viral infection (<xref rid="b5-ETM-25-4-11857 b6-ETM-25-4-11857 b7-ETM-25-4-11857" ref-type="bibr">5-7</xref>). Among them, IFITM3 has the strongest antiviral effect. It blocks fusion with the host cellular membranes in a broad spectrum of enveloped viruses, such as SARS-CoV, influenza, human immunodeficiency virus (HIV), Ebola and Zika (<xref rid="b5-ETM-25-4-11857 b6-ETM-25-4-11857 b7-ETM-25-4-11857" ref-type="bibr">5-7</xref>). The human <italic>IFITM3</italic>, located on chromosome 11p15.5, is composed of two exons and one intron. The single nucleotide polymorphism (SNP) rs12252-C allele of <italic>IFITM3</italic> truncates the protein, leading to decreased restriction of virus replication <italic>in vitro</italic> (<xref rid="b8-ETM-25-4-11857" ref-type="bibr">8</xref>). A meta-analysis indicated that this SNP may be associated with severe influenza infection (<xref rid="b9-ETM-25-4-11857" ref-type="bibr">9</xref>).</p>
<p>Recently, studies have investigated the association of the <italic>IFITM3</italic> rs12252 polymorphism with COVID-19 severity (<xref rid="b10-ETM-25-4-11857 b11-ETM-25-4-11857 b12-ETM-25-4-11857 b13-ETM-25-4-11857 b14-ETM-25-4-11857" ref-type="bibr">10-14</xref>). However, the findings are inconsistent. Such inconsistency may be due partly to population differences in genotype distribution, insufficient power, a small effect of the <italic>IFITM3</italic> rs12252 polymorphism on COVID-19 severity and false-positive results. Therefore, a meta-analysis of published studies was performed to investigate whether the <italic>IFITM3</italic> rs12252 polymorphism is associated with COVID-19 severity.</p>
</sec>
<sec sec-type="Materials|methods">
<title>Materials and methods</title>
<sec>
<title/>
<sec>
<title>Searching</title>
<p>Major databases and preprint servers, including PubMed (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://pubmed.ncbi.nlm.nih.gov">pubmed.ncbi.nlm.nih.gov</ext-link>), EMBASE (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.embase.com">https://www.embase.com</ext-link>), China National Knowledge Infrastructure (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.cnki.net">https://www.cnki.net</ext-link>), Wanfang (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.wanfangdata.com.cn">https://www.wanfangdata.com.cn</ext-link>), MedRxiv (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.medrxiv.org">https://www.medrxiv.org</ext-link>) and BioRxiv (<ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.biorxiv.org">https://www.biorxiv.org</ext-link>), were searched for studies concerning <italic>IFITM3</italic> and COVID-19. The last search update was performed on March 30, 2022. The search strategy is supplied in <xref rid="SD1-ETM-25-4-11857" ref-type="supplementary-material">Appendix S1</xref>. No language restrictions were applied. Manual searching was conducted for references of relevant reviews and included articles.</p>
</sec>
<sec>
<title>Study selection</title>
<p>Studies that were included met the following criteria: i) Evaluated the association between <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity; ii) cohort or case-control study; iii) contained sufficient data to calculate odds ratio (OR) and iv) COVID-19 infection was clearly defined. COVID-19 was diagnosed based on symptoms and laboratory tests. Laboratory confirmation was defined as a positive result using reverse transcription PCR, serological tests (anti-SARS-CoV-2 IgM) or both. Studies were excluded when they were: i) Review articles, comments, responses or case reports; ii) not associated with <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity or iii) non-human studies. When there were multiple studies involving the same or overlapping population, only the most recent study with the largest sample size was included. A total of two authors (KY and JW) assessed each study independently. The titles and abstracts of all citations were screened. Then, full texts of relevant citations were examined for inclusion. Disagreements between reviewers were resolved through discussion with a third author (WW). <xref rid="f1-ETM-25-4-11857" ref-type="fig">Fig. 1</xref> outlines the study selection process that led to the final five studies in the present meta-analysis.</p>
</sec>
<sec>
<title>Data extraction and quality assessment</title>
<p>A total of two authors (KY and JW) independently extracted the following information from each included study: Study design, ethnicity, definition and number of mild-to-moderate and severe cases, age, sex, confounding factors by matching or adjustment, genotyping method, frequency of genotype and consistency of genotype frequencies with Hardy-Weinberg equilibrium (HWE) in control subjects without COVID-19 or mild-to-moderate COVID-19 cases.</p>
<p>A total of two authors (KY and JW) independently assessed the methodological quality of each included case-control study using the Newcastle Ottawa Scale (NOS) for selection, comparability and exposure. The NOS scores ranged from 0 to 9 and a score &#x2265;7 indicated high quality (<xref rid="b15-ETM-25-4-11857" ref-type="bibr">15</xref>). Disagreements were resolved as aforementioned.</p>
</sec>
<sec>
<title>Statistical analysis</title>
<p>ORs with their corresponding 95&#x0025; confidence intervals (CIs) were calculated to assess the strength of the association between the <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity. When mortality data was available, the association between <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 mortality was also assessed. The associations were examined under three genetic models: Additive (CC vs. TT), dominant (CC/CT vs. TT) and recessive (CC vs. CT/TT). HWE was evaluated using &#x03C7;<sup>2</sup> test and P&#x003C;0.05 was considered to indicate a statistically significant difference. Sensitivity analysis was performed using the one-study remove approach to assess the impact of each study on the combined effect.</p>
<p>Between-study heterogeneity was evaluated using Cochran&#x0027;s Q test and <italic>I</italic><sup>2</sup> statistic. If the P-value for the Q test was &#x003C;0.10 or if the <italic>I</italic><sup>2</sup> statistic was &#x2265;50&#x0025;, significant heterogeneity was considered and the random-effect model was used. Otherwise, the fixed-effect model was used. Egger&#x0027;s test and Begg&#x0027;s funnel plot were not used to provide a diagnosis of the potential publication bias as there were only five studies included in the meta-analysis (<xref rid="b16-ETM-25-4-11857" ref-type="bibr">16</xref>). All statistical analyses were performed with Stata 15.0 (StataCorp LP). A two-sided P&#x003C;0.05 was considered to indicate a statistically significant difference. The performance and reporting of the present meta-analysis complied with the Meta-analyses Of Observational Studies in Epidemiology statement (<xref rid="SD2-ETM-25-4-11857" ref-type="supplementary-material">Appendix S2</xref>) (<xref rid="b17-ETM-25-4-11857" ref-type="bibr">17</xref>).</p>
</sec>
</sec>
</sec>
<sec sec-type="Results">
<title>Results</title>
<sec>
<title/>
<sec>
<title>Characteristics of included studies</title>
<p>A total of five independent studies were identified regarding <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity (<xref rid="f1-ETM-25-4-11857" ref-type="fig">Fig. 1</xref>). These five studies were published from 2020 to 2021, with four in the English language and one in Chinese. A total of two studies were conducted in the Chinese population (<xref rid="b10-ETM-25-4-11857" ref-type="bibr">10</xref>,<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>), one in the Saudi population (<xref rid="b12-ETM-25-4-11857" ref-type="bibr">12</xref>), one in the Spanish population (<xref rid="b13-ETM-25-4-11857" ref-type="bibr">13</xref>) and one in the German population (<xref rid="b14-ETM-25-4-11857" ref-type="bibr">14</xref>). In total, 2,110 patients with COVID-19 were included. Of these, 1,443 were mild-to-moderate cases and 667 were severe cases, including 121 deaths. The definition of severity was not identical across studies (<xref rid="SD3-ETM-25-4-11857" ref-type="supplementary-material">Appendix S3</xref>). All studies but one showed that patients with severe cases had older ages compared with mild-to-moderate cases (<xref rid="b14-ETM-25-4-11857" ref-type="bibr">14</xref>). A total of three studies genotyped healthy controls or controls without COVID-19 (<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>,<xref rid="b13-ETM-25-4-11857" ref-type="bibr">13</xref>,<xref rid="b14-ETM-25-4-11857" ref-type="bibr">14</xref>). The <italic>IFITM3</italic> rs12252 C allele frequency was higher in the Chinese population compared with Caucasian population (49.2-55.4&#x0025; vs. 2.8-9.6&#x0025;, respectively; <xref rid="tI-ETM-25-4-11857" ref-type="table">Table I</xref>). All studies were consistent with HWE. Detailed characteristics of the five studies are described in <xref rid="tI-ETM-25-4-11857" ref-type="table">Table I</xref>. NOS scores of all included studies ranged from 8 to 9, which indicated good quality (<xref rid="SD4-ETM-25-4-11857" ref-type="supplementary-material">Appendix S4</xref>).</p>
</sec>
<sec>
<title>Association between IFITM3 rs12252 polymorphism and COVID-19 severity</title>
<p>Under each genetic model, no significant heterogeneity was detected by the Q test and <italic>I</italic><sup>2</sup> statistic (<xref rid="f2-ETM-25-4-11857" ref-type="fig">Fig. 2A-C</xref>). Thus, in the meta-analysis, the fixed-effect model was used for each genetic model. Only under the recessive model (CC vs. CT/TT) was a significant association between the <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity observed. Overall, the OR of developing severe COVID-19 was 1.97 (95&#x0025; CI, 1.06-3.69) in patients carrying the CC genotype compared with those with other genotypes (CT/TT; <xref rid="f2-ETM-25-4-11857" ref-type="fig">Fig. 2C</xref>). The association was not observed under the additive (CC vs. TT) or the dominant model (CC/CT vs. TT; <xref rid="f2-ETM-25-4-11857" ref-type="fig">Fig. 2A</xref> and <xref rid="f2-ETM-25-4-11857" ref-type="fig">B</xref>).</p>
<p>The Chinese population had a significantly higher frequency of <italic>IFITM3</italic> rs12252 C allele compared with the Caucasian population. Stratified analysis by ethnicity showed that only in the Chinese population was the CC genotype associated with severe COVID-19 (CC vs. CT/TT; OR=2.84; 95&#x0025; CI, 1.34-6.04). This association was not observed in the Caucasian population (<xref rid="tII-ETM-25-4-11857" ref-type="table">Table II</xref>).</p>
</sec>
<sec>
<title>Association between IFITM3 rs12252 polymorphism and COVID-19 mortality</title>
<p>A total of four studies included <italic>IFITM3</italic> rs12252 polymorphism data for patients who died with COVID-19. In total, 121 patients who died and 1,989 who survived were included to assess its association with COVID-19 mortality. Under each genetic model, no significant heterogeneity was detected and the fixed model was used (<xref rid="f3-ETM-25-4-11857" ref-type="fig">Fig. 3A-C</xref>). Overall, the CC genotype of <italic>IFITM3</italic> rs12252 was strongly associated with increased COVID-19 mortality risk compared with the CT/TT genotype &#x005B;recessive model (CC vs. CT/TT); OR=4.61; 95&#x0025; CI, 1.44-14.75; <xref rid="f3-ETM-25-4-11857" ref-type="fig">Fig. 3C</xref>&#x005D;. Compared with the TT genotype, the CC/CT genotype was associated with increased COVID-19 mortality risk &#x005B;dominant model (CC/CT vs. TT); OR=1.75; 95&#x0025; CI, 1.11-2.75; <xref rid="f3-ETM-25-4-11857" ref-type="fig">Fig. 3B</xref>&#x005D;. This trend was observed when comparing the CC and TT genotype but it was not statistically significant &#x005B;the additive model (CC vs. TT); OR=3.33; 95&#x0025; CI, 0.85-12.96; <xref rid="f3-ETM-25-4-11857" ref-type="fig">Fig. 3A</xref>&#x005D;.</p>
<p>Stratified analysis by ethnicity showed that in the Chinese population the CC genotype of <italic>IFITM3</italic> rs12252 was strongly associated with increased COVID-19 mortality risk compared with the CT/TT genotype (CC vs. CT/TT; OR=7.91; 95&#x0025; CI, 1.29-48.44). In the Caucasian population, the CC/CT genotype was associated with increased COVID-19 mortality risk compared with the TT genotype (CC/CT vs. TT; OR=1.73; 95&#x0025; CI, 1.09-2.75; <xref rid="tII-ETM-25-4-11857" ref-type="table">Table II</xref>). Using other genetic models, the association between <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 mortality was not observed in either the Chinese or Caucasian population (<xref rid="tII-ETM-25-4-11857" ref-type="table">Table II</xref>).</p>
</sec>
<sec>
<title>Sensitivity analysis</title>
<p>Sensitivity analysis was performed to assess the impact of each study on the pooled results by omitting individual studies in turn (<xref rid="tIII-ETM-25-4-11857" ref-type="table">Table III</xref>). The pooled OR of developing severe COVID-19 was sensitive to the two Chinese studies (<xref rid="b10-ETM-25-4-11857" ref-type="bibr">10</xref>,<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>) and for COVID-19 mortality was sensitive to Pan <italic>et al</italic> (<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>) and Alghamdi <italic>et al</italic> (<xref rid="b12-ETM-25-4-11857" ref-type="bibr">12</xref>).</p>
</sec>
</sec>
</sec>
<sec sec-type="Discussion">
<title>Discussion</title>
<p>Recently, the association between the <italic>IFITM3</italic> rs12252 polymorphism and COVID-19 severity has been investigated in several studies but the results were inconsistent (<xref rid="b10-ETM-25-4-11857 b11-ETM-25-4-11857 b12-ETM-25-4-11857 b13-ETM-25-4-11857 b14-ETM-25-4-11857" ref-type="bibr">10-14</xref>). To the best of our knowledge, the present study is the first meta-analysis conducted on the aforementioned association. The current meta-analysis, which pooled five studies with 2,110 patients, showed that the CC genotype of <italic>IFITM3</italic> rs12252 was associated with increased risk of severe COVID-19 and mortality. Subgroup analyses revealed that this association was strong in the Chinese population. Larger-scale studies are required to determine whether genotyping for rs12252 SNP of <italic>IFITM3</italic> in Chinese and other Asian patients infected with SARS-Cov-2 predicts those who might progress to severe disease. Useful tools combining this SNP with other risk factors may be developed to improve prognosis of the patients by early targeted intervention.</p>
<p>Notably, the CC genotype of <italic>IFITM3</italic> rs12252 is rare in Europeans (0.3&#x0025;) and common in Asians (25-44&#x0025;) (<xref rid="b8-ETM-25-4-11857" ref-type="bibr">8</xref>,<xref rid="b18-ETM-25-4-11857" ref-type="bibr">18</xref>). Thus, it is possible that the power of the present meta-analysis may have been insufficient to detect an effect of the CC genotype in the Caucasian population. This was indicated by a lower but statistically significant OR regarding COVID-19 mortality when patients with CC/CT and TT genotypes were compared in the Caucasian population (OR=1.73; 95&#x0025; CI, 1.09-2.75). Similar results have been reported for Caucasian patients with influenza, in which studies found no or weak association between <italic>IFITM3</italic> rs12252 polymorphism and disease severity (<xref rid="b19-ETM-25-4-11857" ref-type="bibr">19</xref>,<xref rid="b20-ETM-25-4-11857" ref-type="bibr">20</xref>).</p>
<p>IFITM3 is a virus restriction factor mediating cellular resistance to multiple classes of enveloped viral pathogens that enter cells via the acidic endosome (<xref rid="b7-ETM-25-4-11857" ref-type="bibr">7</xref>). IFITM3 inhibits human coronaviruses, including SARS-CoV-1 and Middle East respiratory syndrome coronavirus, as well as SARS-CoV-2 (<xref rid="b21-ETM-25-4-11857" ref-type="bibr">21</xref>,<xref rid="b22-ETM-25-4-11857" ref-type="bibr">22</xref>). Previous studies showed an increased homozygosity of the minor C allele of SNP rs12252 in <italic>IFITM3</italic> in patients with severe viral infection, such as influenza (<xref rid="b18-ETM-25-4-11857" ref-type="bibr">18</xref>), cytomegalovirus (<xref rid="b23-ETM-25-4-11857" ref-type="bibr">23</xref>), enterovirus (<xref rid="b24-ETM-25-4-11857" ref-type="bibr">24</xref>), Hantaan virus (<xref rid="b25-ETM-25-4-11857" ref-type="bibr">25</xref>) and HIV (<xref rid="b26-ETM-25-4-11857" ref-type="bibr">26</xref>). SNP rs12252-C allele encodes a splice acceptor site of the human <italic>IFITM3</italic> gene. Everitt <italic>et al</italic> (<xref rid="b8-ETM-25-4-11857" ref-type="bibr">8</xref>) found that the rs12252-C allele may be associated with a truncated protein with an N-terminal 21 amino acid deletion, which may lead to decreased restriction of virus replication <italic>in vitro</italic>. However, other evidence does not support the hypothesis that CC genotype carriers express truncated <italic>IFITM3</italic> (<xref rid="b27-ETM-25-4-11857" ref-type="bibr">27</xref>); full-length transcript/protein is dominant in all rs12252 genotypes (<xref rid="b27-ETM-25-4-11857" ref-type="bibr">27</xref>). It is hypothesized that rs12252 may be in linkage disequilibrium with a causative SNP near the <italic>IFITM3</italic> locus.</p>
<p>The primary limitation of the present meta-analysis is that it only included five studies with a relatively small size. Thus, the findings in the current meta-analysis are not robust. Sensitivity analysis in the present study also indicated this. Larger cohort studies are needed to confirm the genetic association with COVID-19 severity. As with most meta-analyses, another limitation of the present study is that it is based on unadjusted estimates. Individual information was not available to adjust for confounding factors, such as age, sex and underlying diseases. Finally, all patients included in the present meta-analysis were infected with early strains of SARS-CoV-2 and vaccination coverage was relatively low at that time. Whether and to what extent <italic>IFITM3</italic> rs12252 polymorphism has an effect on COVID-19 needs to be investigated as the virus mutates and herd immunity develops (<xref rid="b28-ETM-25-4-11857 b29-ETM-25-4-11857 b30-ETM-25-4-11857" ref-type="bibr">28-30</xref>).</p>
<p>In conclusion, the present meta-analysis suggested that <italic>IFTM3</italic>-rs12252 CC genotype was significantly associated with increased risks of severe COVID-19 and mortality in the Chinese population and that the <italic>IFTM3</italic>-rs12252 C allele may be associated with increased risk of COVID-19 mortality in the Caucasian population. Large-scale studies are needed to confirm the genetic association with COVID-19 severity in different global populations.</p>
</sec>
<sec sec-type="supplementary-material">
<title>Supplementary Material</title>
<supplementary-material id="SD1-ETM-25-4-11857" content-type="local-data">
<caption>
<title>Search strategies</title>
</caption>
<media mimetype="application" mime-subtype="pdf" xlink:href="Supplementary_Data.pdf"/>
</supplementary-material>
<supplementary-material id="SD2-ETM-25-4-11857" content-type="local-data">
<caption>
<title>Checklist for Meta-analyses of Observational Studies.</title>
</caption>
<media mimetype="application" mime-subtype="pdf" xlink:href="Supplementary_Data.pdf"/>
</supplementary-material>
<supplementary-material id="SD3-ETM-25-4-11857" content-type="local-data">
<caption>
<title>Definition of severe COVID-19 of included studies</title>
</caption>
<media mimetype="application" mime-subtype="pdf" xlink:href="Supplementary_Data.pdf"/>
</supplementary-material>
<supplementary-material id="SD4-ETM-25-4-11857" content-type="local-data">
<caption>
<title>Quality of included studies assessed using the Newcastle Ottawa Scale (8).</title>
</caption>
<media mimetype="application" mime-subtype="pdf" xlink:href="Supplementary_Data.pdf"/>
</supplementary-material>
</sec>
</body>
<back>
<ack>
<title>Acknowledgements</title>
<p>Not applicable.</p>
</ack>
<sec sec-type="data-availability">
<title>Availability of data and materials</title>
<p>All data generated or analyzed during this study are included in this published article.</p>
</sec>
<sec>
<title>Authors&#x0027; contributions</title>
<p>KY, JW, HL and WW conceived and designed the study, collected, analyzed and interpretated data and wrote and revised the manuscript. KY and WW confirm the authenticity of all the raw data. All authors have read and approved the final manuscript.</p>
</sec>
<sec>
<title>Ethics approval and consent to participate</title>
<p>Not applicable.</p>
</sec>
<sec>
<title>Patient consent for publication</title>
<p>Not applicable.</p>
</sec>
<sec sec-type="COI-statement">
<title>Competing interests</title>
<p>The authors declare that they have no competing interests.</p>
</sec>
<ref-list>
<title>References</title>
<ref id="b1-ETM-25-4-11857"><label>1</label><element-citation publication-type="journal"><comment>World Health Organization: WHO Coronavirus (COVID-19) Dashboard. <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://covid19.who.int/">https://covid19.who.int/</ext-link>. Accessed April 9, 2022.</comment></element-citation></ref>
<ref id="b2-ETM-25-4-11857"><label>2</label><element-citation publication-type="journal"><comment>The National Health Commission of China: The diagnosis and treatment of COVID-19. <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.nhc.gov.cn/yzygj/s7653p/202203/b74ade1ba4494583805a3d2e40093d88.shtml">http://www.nhc.gov.cn/yzygj/s7653p/202203/b74ade1ba4494583805a3d2e40093d88.shtml</ext-link>. Accessed 1 April 2022, 2022.</comment></element-citation></ref>
<ref id="b3-ETM-25-4-11857"><label>3</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Ferreira de Ara&#x00FA;jo</surname><given-names>JL</given-names></name><name><surname>Menezes</surname><given-names>D</given-names></name><name><surname>Saraiva Duarte</surname><given-names>JM</given-names></name><name><surname>de Lima Ferreira</surname><given-names>L</given-names></name><name><surname>Santana de Aguiar</surname><given-names>R</given-names></name><name><surname>Pedra de Souza</surname><given-names>R</given-names></name></person-group><article-title>Systematic review of host genetic association with Covid-19 prognosis and susceptibility: What have we learned in 2020?</article-title><source>Rev Med Virol</source><volume>32</volume><issue>e2283</issue><year>2022</year><pub-id pub-id-type="pmid">34338380</pub-id><pub-id pub-id-type="doi">10.1002/rmv.2283</pub-id></element-citation></ref>
<ref id="b4-ETM-25-4-11857"><label>4</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Suh</surname><given-names>S</given-names></name><name><surname>Lee</surname><given-names>S</given-names></name><name><surname>Gym</surname><given-names>H</given-names></name><name><surname>Yoon</surname><given-names>S</given-names></name><name><surname>Park</surname><given-names>S</given-names></name><name><surname>Cha</surname><given-names>J</given-names></name><name><surname>Kwon</surname><given-names>DH</given-names></name><name><surname>Yang</surname><given-names>Y</given-names></name><name><surname>Jee</surname><given-names>SH</given-names></name></person-group><article-title>A systematic review on papers that study on single nucleotide polymorphism that affects coronavirus 2019 severity</article-title><source>BMC Infect Dis</source><volume>22</volume><issue>47</issue><year>2022</year><pub-id pub-id-type="pmid">35022007</pub-id><pub-id pub-id-type="doi">10.1186/s12879-022-07034-w</pub-id></element-citation></ref>
<ref id="b5-ETM-25-4-11857"><label>5</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Brass</surname><given-names>AL</given-names></name><name><surname>Huang</surname><given-names>IC</given-names></name><name><surname>Benita</surname><given-names>Y</given-names></name><name><surname>John</surname><given-names>SP</given-names></name><name><surname>Krishnan</surname><given-names>MN</given-names></name><name><surname>Feeley</surname><given-names>EM</given-names></name><name><surname>Ryan</surname><given-names>BJ</given-names></name><name><surname>Weyer</surname><given-names>JL</given-names></name><name><surname>van der Weyden</surname><given-names>L</given-names></name><name><surname>Fikrig</surname><given-names>E</given-names></name><etal/></person-group><article-title>The IFITM proteins mediate cellular resistance to influenza A H1N1 virus, West Nile virus, and dengue virus</article-title><source>Cell</source><volume>139</volume><fpage>1243</fpage><lpage>1254</lpage><year>2009</year><pub-id pub-id-type="pmid">20064371</pub-id><pub-id pub-id-type="doi">10.1016/j.cell.2009.12.017</pub-id></element-citation></ref>
<ref id="b6-ETM-25-4-11857"><label>6</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Perreira</surname><given-names>JM</given-names></name><name><surname>Chin</surname><given-names>CR</given-names></name><name><surname>Feeley</surname><given-names>EM</given-names></name><name><surname>Brass</surname><given-names>AL</given-names></name></person-group><article-title>IFITMs restrict the replication of multiple pathogenic viruses</article-title><source>J Mol Biol</source><volume>425</volume><fpage>4937</fpage><lpage>4955</lpage><year>2013</year><pub-id pub-id-type="pmid">24076421</pub-id><pub-id pub-id-type="doi">10.1016/j.jmb.2013.09.024</pub-id></element-citation></ref>
<ref id="b7-ETM-25-4-11857"><label>7</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Ren</surname><given-names>L</given-names></name><name><surname>Du</surname><given-names>S</given-names></name><name><surname>Xu</surname><given-names>W</given-names></name><name><surname>Li</surname><given-names>T</given-names></name><name><surname>Wu</surname><given-names>S</given-names></name><name><surname>Jin</surname><given-names>N</given-names></name><name><surname>Li</surname><given-names>C</given-names></name></person-group><article-title>Current progress on host antiviral factor IFITMs</article-title><source>Front Immunol</source><volume>11</volume><issue>543444</issue><year>2020</year><pub-id pub-id-type="pmid">33329509</pub-id><pub-id pub-id-type="doi">10.3389/fimmu.2020.543444</pub-id></element-citation></ref>
<ref id="b8-ETM-25-4-11857"><label>8</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Everitt</surname><given-names>AR</given-names></name><name><surname>Clare</surname><given-names>S</given-names></name><name><surname>Pertel</surname><given-names>T</given-names></name><name><surname>John</surname><given-names>SP</given-names></name><name><surname>Wash</surname><given-names>RS</given-names></name><name><surname>Smith</surname><given-names>SE</given-names></name><name><surname>Chin</surname><given-names>CR</given-names></name><name><surname>Feeley</surname><given-names>EM</given-names></name><name><surname>Sims</surname><given-names>JS</given-names></name><name><surname>Adams</surname><given-names>DJ</given-names></name><etal/></person-group><article-title>IFITM3 restricts the morbidity and mortality associated with influenza</article-title><source>Nature</source><volume>484</volume><fpage>519</fpage><lpage>523</lpage><year>2012</year><pub-id pub-id-type="pmid">22446628</pub-id><pub-id pub-id-type="doi">10.1038/nature10921</pub-id></element-citation></ref>
<ref id="b9-ETM-25-4-11857"><label>9</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Prabhu</surname><given-names>SS</given-names></name><name><surname>Chakraborty</surname><given-names>TT</given-names></name><name><surname>Kumar</surname><given-names>N</given-names></name><name><surname>Banerjee</surname><given-names>I</given-names></name></person-group><article-title>Association between IFITM3 rs12252 polymorphism and influenza susceptibility and severity: A meta-analysis</article-title><source>Gene</source><volume>674</volume><fpage>70</fpage><lpage>79</lpage><year>2018</year><pub-id pub-id-type="pmid">29940276</pub-id><pub-id pub-id-type="doi">10.1016/j.gene.2018.06.070</pub-id></element-citation></ref>
<ref id="b10-ETM-25-4-11857"><label>10</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname><given-names>Y</given-names></name><name><surname>Qin</surname><given-names>L</given-names></name><name><surname>Zhao</surname><given-names>Y</given-names></name><name><surname>Zhang</surname><given-names>P</given-names></name><name><surname>Xu</surname><given-names>B</given-names></name><name><surname>Li</surname><given-names>K</given-names></name><name><surname>Liang</surname><given-names>L</given-names></name><name><surname>Zhang</surname><given-names>C</given-names></name><name><surname>Dai</surname><given-names>Y</given-names></name><name><surname>Feng</surname><given-names>Y</given-names></name><etal/></person-group><article-title>Interferon-induced transmembrane protein 3 genetic variant rs12252-C associated with disease severity in coronavirus disease 2019</article-title><source>J Infect Dis</source><volume>222</volume><fpage>34</fpage><lpage>37</lpage><year>2020</year><pub-id pub-id-type="pmid">32348495</pub-id><pub-id pub-id-type="doi">10.1093/infdis/jiaa224</pub-id></element-citation></ref>
<ref id="b11-ETM-25-4-11857"><label>11</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Pan</surname><given-names>Y</given-names></name><name><surname>Li</surname><given-names>F</given-names></name><name><surname>Wang</surname><given-names>X</given-names></name><name><surname>Liang</surname><given-names>Z</given-names></name><name><surname>Cui</surname><given-names>S</given-names></name><name><surname>Peng</surname><given-names>X</given-names></name><name><surname>Lu</surname><given-names>G</given-names></name><name><surname>Zhao</surname><given-names>J</given-names></name><name><surname>Liu</surname><given-names>Y</given-names></name><name><surname>Wang</surname><given-names>Q</given-names></name><name><surname>Zhang</surname><given-names>D</given-names></name></person-group><article-title>Association between rs12252 polymorphism in IFITM3 gene and COVID-19</article-title><source>Int J Virology</source><volume>28</volume><fpage>192</fpage><lpage>195</lpage><year>2021</year></element-citation></ref>
<ref id="b12-ETM-25-4-11857"><label>12</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Alghamdi</surname><given-names>J</given-names></name><name><surname>Alaamery</surname><given-names>M</given-names></name><name><surname>Barhoumi</surname><given-names>T</given-names></name><name><surname>Rashid</surname><given-names>M</given-names></name><name><surname>Alajmi</surname><given-names>H</given-names></name><name><surname>Aljasser</surname><given-names>N</given-names></name><name><surname>Alhendi</surname><given-names>Y</given-names></name><name><surname>Alkhalaf</surname><given-names>H</given-names></name><name><surname>Alqahtani</surname><given-names>H</given-names></name><name><surname>Algablan</surname><given-names>O</given-names></name><etal/></person-group><article-title>Interferon-induced transmembrane protein-3 genetic variant rs12252 is associated with COVID-19 mortality</article-title><source>Genomics</source><volume>113</volume><fpage>1733</fpage><lpage>1741</lpage><year>2021</year><pub-id pub-id-type="pmid">33838280</pub-id><pub-id pub-id-type="doi">10.1016/j.ygeno.2021.04.002</pub-id></element-citation></ref>
<ref id="b13-ETM-25-4-11857"><label>13</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Cuesta-Llavona</surname><given-names>E</given-names></name><name><surname>Albaiceta</surname><given-names>GM</given-names></name><name><surname>Garc&#x00ED;a-Clemente</surname><given-names>M</given-names></name><name><surname>Duarte-Herrera</surname><given-names>ID</given-names></name><name><surname>Amado-Rodr&#x00ED;guez</surname><given-names>L</given-names></name><name><surname>Hermida-Valverde</surname><given-names>T</given-names></name><name><surname>Enr&#x00ED;quez-Rodriguez</surname><given-names>AI</given-names></name><name><surname>Hern&#x00E1;ndez-Gonz&#x00E1;lez</surname><given-names>C</given-names></name><name><surname>Mel&#x00F3;n</surname><given-names>S</given-names></name><name><surname>Alvarez-Arg&#x00FC;elles</surname><given-names>ME</given-names></name><etal/></person-group><article-title>Association between the interferon-induced transmembrane protein 3 gene (IFITM3) rs34481144 / rs12252 haplotypes and COVID-19</article-title><source>Curr Res Virol Sci</source><volume>2</volume><issue>100016</issue><year>2021</year><pub-id pub-id-type="pmid">34870250</pub-id><pub-id pub-id-type="doi">10.1016/j.crviro.2021.100016</pub-id></element-citation></ref>
<ref id="b14-ETM-25-4-11857"><label>14</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sch&#x00F6;nfelder</surname><given-names>K</given-names></name><name><surname>Breuckmann</surname><given-names>K</given-names></name><name><surname>Elsner</surname><given-names>C</given-names></name><name><surname>Dittmer</surname><given-names>U</given-names></name><name><surname>Fistera</surname><given-names>D</given-names></name><name><surname>Herbstreit</surname><given-names>F</given-names></name><name><surname>Risse</surname><given-names>J</given-names></name><name><surname>Schmidt</surname><given-names>K</given-names></name><name><surname>Sutharsan</surname><given-names>S</given-names></name><name><surname>Taube</surname><given-names>C</given-names></name><etal/></person-group><article-title>The influence of IFITM3 polymorphisms on susceptibility to SARS-CoV-2 infection and severity of COVID-19</article-title><source>Cytokine</source><volume>142</volume><issue>155492</issue><year>2021</year><pub-id pub-id-type="pmid">33711707</pub-id><pub-id pub-id-type="doi">10.1016/j.cyto.2021.155492</pub-id></element-citation></ref>
<ref id="b15-ETM-25-4-11857"><label>15</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Wells</surname><given-names>GA</given-names></name><name><surname>Shea</surname><given-names>B</given-names></name><name><surname>O&#x0027;Connell</surname><given-names>D</given-names></name><name><surname>Peterson</surname><given-names>J</given-names></name><name><surname>Welch</surname><given-names>V</given-names></name><name><surname>Losos</surname><given-names>M</given-names></name><name><surname>Tugwell</surname><given-names>P</given-names></name></person-group><comment>The Newcastle-Ottawa scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. Ottawa Hospital Research Institute, Ottawa, ON, 2000. <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp">http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp</ext-link>.</comment></element-citation></ref>
<ref id="b16-ETM-25-4-11857"><label>16</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Harbord</surname><given-names>RM</given-names></name><name><surname>Harris</surname><given-names>RJ</given-names></name><name><surname>Sterne</surname><given-names>JAC</given-names></name></person-group><article-title>Updated tests for small-study effects in meta-analyses</article-title><source>Stata J</source><volume>9</volume><fpage>197</fpage><lpage>210</lpage><year>2009</year></element-citation></ref>
<ref id="b17-ETM-25-4-11857"><label>17</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Stroup</surname><given-names>DF</given-names></name><name><surname>Berlin</surname><given-names>JA</given-names></name><name><surname>Morton</surname><given-names>SC</given-names></name><name><surname>Olkin</surname><given-names>I</given-names></name><name><surname>Williamson</surname><given-names>GD</given-names></name><name><surname>Rennie</surname><given-names>D</given-names></name><name><surname>Moher</surname><given-names>D</given-names></name><name><surname>Becker</surname><given-names>BJ</given-names></name><name><surname>Sipe</surname><given-names>TA</given-names></name><name><surname>Thacker</surname><given-names>SB</given-names></name></person-group><article-title>Meta-analysis of observational studies in epidemiology: A proposal for reporting. Meta-analysis Of observational studies in epidemiology (MOOSE) group</article-title><source>JAMA</source><volume>283</volume><fpage>2008</fpage><lpage>2012</lpage><year>2000</year><pub-id pub-id-type="pmid">10789670</pub-id><pub-id pub-id-type="doi">10.1001/jama.283.15.2008</pub-id></element-citation></ref>
<ref id="b18-ETM-25-4-11857"><label>18</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname><given-names>YH</given-names></name><name><surname>Zhao</surname><given-names>Y</given-names></name><name><surname>Li</surname><given-names>N</given-names></name><name><surname>Peng</surname><given-names>YC</given-names></name><name><surname>Giannoulatou</surname><given-names>E</given-names></name><name><surname>Jin</surname><given-names>RH</given-names></name><name><surname>Yan</surname><given-names>HP</given-names></name><name><surname>Wu</surname><given-names>H</given-names></name><name><surname>Liu</surname><given-names>JH</given-names></name><name><surname>Liu</surname><given-names>N</given-names></name><etal/></person-group><article-title>Interferon-induced transmembrane protein-3 genetic variant rs12252-C is associated with severe influenza in Chinese individuals</article-title><source>Nat Commun</source><volume>4</volume><issue>1418</issue><year>2013</year><pub-id pub-id-type="pmid">23361009</pub-id><pub-id pub-id-type="doi">10.1038/ncomms2433</pub-id></element-citation></ref>
<ref id="b19-ETM-25-4-11857"><label>19</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Randolph</surname><given-names>AG</given-names></name><name><surname>Yip</surname><given-names>WK</given-names></name><name><surname>Allen</surname><given-names>EK</given-names></name><name><surname>Rosenberger</surname><given-names>CM</given-names></name><name><surname>Agan</surname><given-names>AA</given-names></name><name><surname>Ash</surname><given-names>SA</given-names></name><name><surname>Zhang</surname><given-names>Y</given-names></name><name><surname>Bhangale</surname><given-names>TR</given-names></name><name><surname>Finkelstein</surname><given-names>D</given-names></name><name><surname>Cvijanovich</surname><given-names>NZ</given-names></name><etal/></person-group><article-title>Evaluation of IFITM3 rs12252 association with severe pediatric influenza infection</article-title><source>J Infect Dis</source><volume>216</volume><fpage>14</fpage><lpage>21</lpage><year>2017</year><pub-id pub-id-type="pmid">28531322</pub-id><pub-id pub-id-type="doi">10.1093/infdis/jix242</pub-id></element-citation></ref>
<ref id="b20-ETM-25-4-11857"><label>20</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>L&#x00F3;pez-Rodr&#x00ED;guez</surname><given-names>M</given-names></name><name><surname>Herrera-Ramos</surname><given-names>E</given-names></name><name><surname>Sol&#x00E9;-Viol&#x00E1;n</surname><given-names>J</given-names></name><name><surname>Ru&#x00ED;z-Hern&#x00E1;ndez</surname><given-names>JJ</given-names></name><name><surname>Border&#x00ED;as</surname><given-names>L</given-names></name><name><surname>Horcajada</surname><given-names>JP</given-names></name><name><surname>Lerma-Chippirraz</surname><given-names>E</given-names></name><name><surname>Rajas</surname><given-names>O</given-names></name><name><surname>Briones</surname><given-names>M</given-names></name><name><surname>P&#x00E9;rez-Gonz&#x00E1;lez</surname><given-names>MC</given-names></name><etal/></person-group><article-title>IFITM3 and severe influenza virus infection. No evidence of genetic association</article-title><source>Eur J Clin Microbiol Infect Dis</source><volume>35</volume><fpage>1811</fpage><lpage>1817</lpage><year>2016</year><pub-id pub-id-type="pmid">27492307</pub-id><pub-id pub-id-type="doi">10.1007/s10096-016-2732-7</pub-id></element-citation></ref>
<ref id="b21-ETM-25-4-11857"><label>21</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Prelli Bozzo</surname><given-names>C</given-names></name><name><surname>Nchioua</surname><given-names>R</given-names></name><name><surname>Volcic</surname><given-names>M</given-names></name><name><surname>Koepke</surname><given-names>L</given-names></name><name><surname>Kr&#x00FC;ger</surname><given-names>J</given-names></name><name><surname>Sch&#x00FC;tz</surname><given-names>D</given-names></name><name><surname>Heller</surname><given-names>S</given-names></name><name><surname>St&#x00FC;rzel</surname><given-names>CM</given-names></name><name><surname>Kmiec</surname><given-names>D</given-names></name><name><surname>Conzelmann</surname><given-names>C</given-names></name><etal/></person-group><article-title>IFITM proteins promote SARS-CoV-2 infection and are targets for virus inhibition in vitro</article-title><source>Nat Commun</source><volume>12</volume><issue>4584</issue><year>2021</year><pub-id pub-id-type="pmid">34321474</pub-id><pub-id pub-id-type="doi">10.1038/s41467-021-24817-y</pub-id></element-citation></ref>
<ref id="b22-ETM-25-4-11857"><label>22</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Shi</surname><given-names>G</given-names></name><name><surname>Kenney</surname><given-names>AD</given-names></name><name><surname>Kudryashova</surname><given-names>E</given-names></name><name><surname>Zani</surname><given-names>A</given-names></name><name><surname>Zhang</surname><given-names>L</given-names></name><name><surname>Lai</surname><given-names>KK</given-names></name><name><surname>Hall-Stoodley</surname><given-names>L</given-names></name><name><surname>Robinson</surname><given-names>RT</given-names></name><name><surname>Kudryashov</surname><given-names>DS</given-names></name><name><surname>Compton</surname><given-names>AA</given-names></name><name><surname>Yount</surname><given-names>JS</given-names></name></person-group><article-title>Opposing activities of IFITM proteins in SARS-CoV-2 infection</article-title><source>EMBO J</source><volume>40</volume><issue>e106501</issue><year>2021</year><pub-id pub-id-type="pmid">33270927</pub-id><pub-id pub-id-type="doi">10.15252/embj.2020106501</pub-id></element-citation></ref>
<ref id="b23-ETM-25-4-11857"><label>23</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Wang</surname><given-names>YS</given-names></name><name><surname>Luo</surname><given-names>QL</given-names></name><name><surname>Guan</surname><given-names>YG</given-names></name><name><surname>Fan</surname><given-names>DY</given-names></name><name><surname>Luan</surname><given-names>GM</given-names></name><name><surname>Jing</surname><given-names>A</given-names></name></person-group><article-title>HCMV infection and IFITM3 rs12252 are associated with Rasmussen&#x0027;s encephalitis disease progression</article-title><source>Ann Clin Transl Neurol</source><volume>8</volume><fpage>558</fpage><lpage>570</lpage><year>2021</year><pub-id pub-id-type="pmid">33465303</pub-id><pub-id pub-id-type="doi">10.1002/acn3.51289</pub-id></element-citation></ref>
<ref id="b24-ETM-25-4-11857"><label>24</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Li</surname><given-names>M</given-names></name><name><surname>Li</surname><given-names>YP</given-names></name><name><surname>Deng</surname><given-names>HL</given-names></name><name><surname>Wang</surname><given-names>MQ</given-names></name><name><surname>Chen</surname><given-names>Y</given-names></name><name><surname>Zhang</surname><given-names>YF</given-names></name><name><surname>Wang</surname><given-names>J</given-names></name><name><surname>Dang</surname><given-names>SS</given-names></name></person-group><article-title>DNA methylation and SNP in IFITM3 are correlated with hand, foot and mouth disease caused by enterovirus 71</article-title><source>Int J Infect Dis</source><volume>105</volume><fpage>199</fpage><lpage>208</lpage><year>2021</year><pub-id pub-id-type="pmid">33596480</pub-id><pub-id pub-id-type="doi">10.1016/j.ijid.2021.02.049</pub-id></element-citation></ref>
<ref id="b25-ETM-25-4-11857"><label>25</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Xu-Yang</surname><given-names>Z</given-names></name><name><surname>Pei-Yu</surname><given-names>B</given-names></name><name><surname>Chuan-Tao</surname><given-names>Y</given-names></name><name><surname>Wei</surname><given-names>Y</given-names></name><name><surname>Hong-Wei</surname><given-names>M</given-names></name><name><surname>Kang</surname><given-names>T</given-names></name><name><surname>Chun-Mei</surname><given-names>Z</given-names></name><name><surname>Ying-Feng</surname><given-names>L</given-names></name><name><surname>Xin</surname><given-names>W</given-names></name><name><surname>Ping-Zhong</surname><given-names>W</given-names></name><etal/></person-group><article-title>Interferon-induced transmembrane protein 3 inhibits Hantaan virus infection, and its single nucleotide polymorphism rs12252 influences the severity of hemorrhagic fever with renal syndrome</article-title><source>Front Immunol</source><volume>7</volume><issue>535</issue><year>2016</year><pub-id pub-id-type="pmid">28096800</pub-id><pub-id pub-id-type="doi">10.3389/fimmu.2016.00535</pub-id></element-citation></ref>
<ref id="b26-ETM-25-4-11857"><label>26</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname><given-names>Y</given-names></name><name><surname>Makvandi-Nejad</surname><given-names>S</given-names></name><name><surname>Qin</surname><given-names>L</given-names></name><name><surname>Zhao</surname><given-names>Y</given-names></name><name><surname>Zhang</surname><given-names>T</given-names></name><name><surname>Wang</surname><given-names>L</given-names></name><name><surname>Repapi</surname><given-names>E</given-names></name><name><surname>Taylor</surname><given-names>S</given-names></name><name><surname>McMichael</surname><given-names>A</given-names></name><name><surname>Li</surname><given-names>N</given-names></name><etal/></person-group><article-title>Interferon-induced transmembrane protein-3 rs12252-C is associated with rapid progression of acute HIV-1 infection in Chinese MSM cohort</article-title><source>AIDS</source><volume>29</volume><fpage>889</fpage><lpage>894</lpage><year>2015</year><pub-id pub-id-type="pmid">25784441</pub-id><pub-id pub-id-type="doi">10.1097/QAD.0000000000000632</pub-id></element-citation></ref>
<ref id="b27-ETM-25-4-11857"><label>27</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Makvandi-Nejad</surname><given-names>S</given-names></name><name><surname>Laurenson-Schafer</surname><given-names>H</given-names></name><name><surname>Wang</surname><given-names>L</given-names></name><name><surname>Wellington</surname><given-names>D</given-names></name><name><surname>Zhao</surname><given-names>Y</given-names></name><name><surname>Jin</surname><given-names>B</given-names></name><name><surname>Qin</surname><given-names>L</given-names></name><name><surname>Kite</surname><given-names>K</given-names></name><name><surname>Moghadam</surname><given-names>HK</given-names></name><name><surname>Song</surname><given-names>C</given-names></name><etal/></person-group><article-title>Lack of truncated IFITM3 transcripts in cells homozygous for the rs12252-C variant that is associated with severe influenza infection</article-title><source>J Infect Dis</source><volume>217</volume><fpage>257</fpage><lpage>262</lpage><year>2018</year><pub-id pub-id-type="pmid">29202190</pub-id><pub-id pub-id-type="doi">10.1093/infdis/jix512</pub-id></element-citation></ref>
<ref id="b28-ETM-25-4-11857"><label>28</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Neagu</surname><given-names>M</given-names></name><name><surname>Calina</surname><given-names>D</given-names></name><name><surname>Docea</surname><given-names>AO</given-names></name><name><surname>Constantin</surname><given-names>C</given-names></name><name><surname>Filippini</surname><given-names>T</given-names></name><name><surname>Vinceti</surname><given-names>M</given-names></name><name><surname>Drakoulis</surname><given-names>N</given-names></name><name><surname>Poulas</surname><given-names>K</given-names></name><name><surname>Nikolouzakis</surname><given-names>TK</given-names></name><name><surname>Spandidos</surname><given-names>DA</given-names></name><name><surname>Tsatsakis</surname><given-names>A</given-names></name></person-group><article-title>Back to basics in COVID-19: Antigens and antibodies-completing the puzzle</article-title><source>J Cell Mol Med</source><volume>25</volume><fpage>4523</fpage><lpage>4533</lpage><year>2021</year><pub-id pub-id-type="pmid">33734600</pub-id><pub-id pub-id-type="doi">10.1111/jcmm.16462</pub-id></element-citation></ref>
<ref id="b29-ETM-25-4-11857"><label>29</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Petrakis</surname><given-names>D</given-names></name><name><surname>Nikolouzakis</surname><given-names>TK</given-names></name><name><surname>Karzi</surname><given-names>V</given-names></name><name><surname>Vardavas</surname><given-names>AI</given-names></name><name><surname>Vardavas</surname><given-names>CI</given-names></name><name><surname>Tsatsakis</surname><given-names>A</given-names></name></person-group><article-title>The growing anthropogenic immune deficit and the COVID-19 pandemic</article-title><source>Public Health Toxicol</source><volume>1</volume><fpage>1</fpage><lpage>5</lpage><year>2021</year></element-citation></ref>
<ref id="b30-ETM-25-4-11857"><label>30</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Tsatsakis</surname><given-names>A</given-names></name><name><surname>Vakonaki</surname><given-names>E</given-names></name><name><surname>Tzatzarakis</surname><given-names>M</given-names></name><name><surname>Flamourakis</surname><given-names>M</given-names></name><name><surname>Nikolouzakis</surname><given-names>TK</given-names></name><name><surname>Poulas</surname><given-names>K</given-names></name><name><surname>Papazoglou</surname><given-names>G</given-names></name><name><surname>Hatzidaki</surname><given-names>E</given-names></name><name><surname>Papanikolaou</surname><given-names>NC</given-names></name><name><surname>Drakoulis</surname><given-names>N</given-names></name><etal/></person-group><article-title>Immune response (IgG) following full inoculation with BNT162b2 COVID-19 mRNA among healthcare professionals</article-title><source>Int J Mol Med</source><volume>48</volume><issue>200</issue><year>2021</year><pub-id pub-id-type="pmid">34515322</pub-id><pub-id pub-id-type="doi">10.3892/ijmm.2021.5033</pub-id></element-citation></ref>
</ref-list>
</back>
<floats-group>
<fig id="f1-ETM-25-4-11857" position="float">
<label>Figure 1</label>
<caption><p>Flow diagram of the study selection process. <italic>IFITM3</italic>, interferon-induced transmembrane protein 3; COVID-19, coronavirus disease 2019.</p></caption>
<graphic xlink:href="etm-25-04-11857-g00.tif" />
</fig>
<fig id="f2-ETM-25-4-11857" position="float">
<label>Figure 2</label>
<caption><p>Forest plots for interferon-induced transmembrane protein 3 rs12252 polymorphism and coronavirus disease 2019 severity using (A) additive, (B) dominant and (C) recessive model. The overall odds ratios (with 95&#x0025; confidence intervals) are labeled.</p></caption>
<graphic xlink:href="etm-25-04-11857-g01.tif" />
</fig>
<fig id="f3-ETM-25-4-11857" position="float">
<label>Figure 3</label>
<caption><p>Forest plots for interferon-induced transmembrane protein 3 rs12252 polymorphism and coronavirus disease 2019 mortality using (A) additive, (B) dominant and (C) recessive model. The overall odds ratios (with 95&#x0025; confidence intervals) are labeled.</p></caption>
<graphic xlink:href="etm-25-04-11857-g02.tif" />
</fig>
<table-wrap id="tI-ETM-25-4-11857" position="float">
<label>Table I</label>
<caption><p>Characteristics of studies included in the meta-analysis.</p></caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="middle" colspan="3">&#x00A0;</th>
<th align="center" valign="middle" colspan="3">Mild-to-moderate</th>
<th align="center" valign="middle" colspan="3">Severe</th>
<th align="center" valign="middle" colspan="5">&#x00A0;</th>
</tr>
<tr>
<th align="left" valign="middle">Study</th>
<th align="center" valign="middle">Population</th>
<th align="center" valign="middle">Genotype method</th>
<th align="center" valign="middle">Male, &#x0025;</th>
<th align="center" valign="middle">Age, years</th>
<th align="center" valign="middle">CC/CT/TT</th>
<th align="center" valign="middle">Male (&#x0025;)</th>
<th align="center" valign="middle">Age, years</th>
<th align="center" valign="middle">CC/CT/TT</th>
<th align="center" valign="middle">Died CC/CT/TT</th>
<th align="center" valign="middle">Control CC/CT/TT</th>
<th align="center" valign="middle">Factors adjusted</th>
<th align="center" valign="middle">C allele, &#x0025;</th>
<th align="center" valign="middle">HWE P-value</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">Zhang <italic>et al</italic>, 2020(<xref rid="b10-ETM-25-4-11857" ref-type="bibr">10</xref>)</td>
<td align="left" valign="middle">Chinese</td>
<td align="left" valign="middle">Sequencing</td>
<td align="center" valign="middle">42.9</td>
<td align="center" valign="middle">43.5 (34.0-56.5)</td>
<td align="center" valign="middle">16/30/10</td>
<td align="center" valign="middle">37.5&#x0025;</td>
<td align="center" valign="middle">67.5 (57.8-74.3)</td>
<td align="center" valign="middle">12/7/5</td>
<td align="center" valign="middle">2/1/0</td>
<td align="center" valign="middle">NA</td>
<td align="center" valign="middle">Age</td>
<td align="center" valign="middle">55.4</td>
<td align="center" valign="middle">&#x003E;0.5</td>
</tr>
<tr>
<td align="left" valign="middle">Pan <italic>et al</italic>, 2021(<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>)</td>
<td align="left" valign="middle">Chinese</td>
<td align="left" valign="middle">Sequencing</td>
<td align="center" valign="middle">54.2</td>
<td align="center" valign="middle">39.5</td>
<td align="center" valign="middle">126/203/105</td>
<td align="center" valign="middle">50.0&#x0025;</td>
<td align="center" valign="middle">51.8</td>
<td align="center" valign="middle">7/2/3</td>
<td align="center" valign="middle">3/0/0</td>
<td align="center" valign="middle">15/34/16</td>
<td align="center" valign="middle">Age</td>
<td align="center" valign="middle">49.2</td>
<td align="center" valign="middle">&#x003E;0.7</td>
</tr>
<tr>
<td align="left" valign="middle">Alghamdi <italic>et al</italic>, 2021<sup><xref rid="tfna-ETM-25-4-11857" ref-type="table-fn">a</xref></sup> (<xref rid="b12-ETM-25-4-11857" ref-type="bibr">12</xref>)</td>
<td align="left" valign="middle">Saudi</td>
<td align="left" valign="middle">Taqman</td>
<td align="center" valign="middle">64.0</td>
<td align="center" valign="middle">30.0</td>
<td align="center" valign="middle">3/82/372</td>
<td align="center" valign="middle">56.0&#x0025;</td>
<td align="center" valign="middle">59.0</td>
<td align="center" valign="middle">1/73/330</td>
<td align="center" valign="middle">0/21/56</td>
<td align="center" valign="middle">NA</td>
<td align="center" valign="middle">Age, sex</td>
<td align="center" valign="middle">9.6</td>
<td align="center" valign="middle">&#x003E;0.5</td>
</tr>
<tr>
<td align="left" valign="middle">Cuesta-Llavona <italic>et al</italic>, 2021(<xref rid="b13-ETM-25-4-11857" ref-type="bibr">13</xref>)</td>
<td align="left" valign="middle">Spanish</td>
<td align="left" valign="middle">Taqman</td>
<td align="center" valign="middle">59.0</td>
<td align="center" valign="middle">64.0&#x00B1;16.0</td>
<td align="center" valign="middle">2/30/300</td>
<td align="center" valign="middle">74.0&#x0025;</td>
<td align="center" valign="middle">67.0&#x00B1;16.0</td>
<td align="center" valign="middle">2/17/133</td>
<td align="center" valign="middle">1/5/32</td>
<td align="center" valign="middle">0/10/172</td>
<td align="center" valign="middle">Age, sex</td>
<td align="center" valign="middle">2.8</td>
<td align="center" valign="middle">&#x003E;0.7</td>
</tr>
<tr>
<td align="left" valign="middle">Sch&#x00F6;nfelder <italic>et al</italic>, 2021(<xref rid="b14-ETM-25-4-11857" ref-type="bibr">14</xref>)</td>
<td align="left" valign="middle">German</td>
<td align="left" valign="middle">Sequencing</td>
<td align="center" valign="middle">52.4</td>
<td align="center" valign="middle">57.0 (18.0-94.0)</td>
<td align="center" valign="middle">2/15/147</td>
<td align="center" valign="middle">73.3&#x0025;</td>
<td align="center" valign="middle">64.0 (26.0-99.0)</td>
<td align="center" valign="middle">0/7/68</td>
<td align="center" valign="middle">NA</td>
<td align="center" valign="middle">0/19/234</td>
<td align="center" valign="middle">Age, sex</td>
<td align="center" valign="middle">3.8</td>
<td align="center" valign="middle">&#x003E;0.5</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn><p>Age is presented as median (interquartile range) for Zhang <italic>et al</italic> (<xref rid="b10-ETM-25-4-11857" ref-type="bibr">10</xref>), mean for Pan <italic>et al</italic> (<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>) and Alghamdi <italic>et al</italic> (<xref rid="b12-ETM-25-4-11857" ref-type="bibr">12</xref>), mean &#x00B1; standard deviation for Cuesta-Llavona <italic>et al</italic> (<xref rid="b13-ETM-25-4-11857" ref-type="bibr">13</xref>) and median (range) for Sch&#x00F6;nfelder <italic>et al</italic> (<xref rid="b14-ETM-25-4-11857" ref-type="bibr">14</xref>).</p></fn>
<fn id="tfna-ETM-25-4-11857"><p><sup>a</sup>Age and sex were estimated based on baseline information. C allele frequency of the <italic>IFITM3</italic> rs12252 polymorphism and HWE were calculated in controls without COVID-19 or else in mild-to-moderate cases. HWE, Hardy-Weinberg equilibrium; NA, not available.</p></fn>
</table-wrap-foot>
</table-wrap>
<table-wrap id="tII-ETM-25-4-11857" position="float">
<label>Table II</label>
<caption><p>Meta-analysis of studies on associations of the <italic>IFITM3</italic> rs12252 polymorphism with COVID-19 severity and mortality.</p></caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="middle">&#x00A0;</th>
<th align="center" valign="middle">&#x00A0;</th>
<th align="center" valign="middle">&#x00A0;</th>
<th align="center" valign="middle" colspan="3">Additive model (CC vs. TT)</th>
<th align="center" valign="middle" colspan="3">Dominant model (CC/CT vs. TT)</th>
<th align="center" valign="middle" colspan="3">Recessive model (CC vs. CT/TT)</th>
</tr>
<tr>
<th align="left" valign="middle">Overall/stratified analysis</th>
<th align="center" valign="middle">No. of studies</th>
<th align="center" valign="middle">No. of patients</th>
<th align="center" valign="middle">OR (95&#x0025; CI)</th>
<th align="center" valign="middle">Z-value</th>
<th align="center" valign="middle">P-value</th>
<th align="center" valign="middle">OR (95&#x0025; CI)</th>
<th align="center" valign="middle">Z-value</th>
<th align="center" valign="middle">P-value</th>
<th align="center" valign="middle">OR (95&#x0025; CI)</th>
<th align="center" valign="middle">Z-value</th>
<th align="center" valign="middle">P-value</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">Severity (severe vs. mild/moderate)</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Overall</td>
<td align="center" valign="middle">5</td>
<td align="center" valign="middle">2,110</td>
<td align="center" valign="middle">1.30 (0.62-2.71)</td>
<td align="center" valign="middle">0.70</td>
<td align="center" valign="middle">0.487</td>
<td align="center" valign="middle">1.02 (0.78-1.34)</td>
<td align="center" valign="middle">0.17</td>
<td align="center" valign="middle">0.862</td>
<td align="center" valign="middle">1.97 (1.06-3.69)</td>
<td align="center" valign="middle">2.13</td>
<td align="center" valign="middle">0.033</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Chinese population</td>
<td align="center" valign="middle">2</td>
<td align="center" valign="middle">526</td>
<td align="center" valign="middle">1.70 (0.66-4.39)</td>
<td align="center" valign="middle">1.10</td>
<td align="center" valign="middle">0.270</td>
<td align="center" valign="middle">0.88 (0.36-2.14)</td>
<td align="center" valign="middle">0.27</td>
<td align="center" valign="middle">0.784</td>
<td align="center" valign="middle">2.84 (1.34-6.04)</td>
<td align="center" valign="middle">2.72</td>
<td align="center" valign="middle">0.007</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Caucasian population</td>
<td align="center" valign="middle">3</td>
<td align="center" valign="middle">1,584</td>
<td align="center" valign="middle">0.80 (0.23-2.83)</td>
<td align="center" valign="middle">0.35</td>
<td align="center" valign="middle">0.730</td>
<td align="center" valign="middle">1.04 (0.78-1.38)</td>
<td align="center" valign="middle">0.27</td>
<td align="center" valign="middle">0.788</td>
<td align="center" valign="middle">0.79 (0.23-2.80)</td>
<td align="center" valign="middle">0.36</td>
<td align="center" valign="middle">0.720</td>
</tr>
<tr>
<td align="left" valign="middle">Mortality (died vs. survived)</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Overall</td>
<td align="center" valign="middle">4</td>
<td align="center" valign="middle">1,871</td>
<td align="center" valign="middle">3.33 (0.85-12.96)</td>
<td align="center" valign="middle">1.73</td>
<td align="center" valign="middle">0.083</td>
<td align="center" valign="middle">1.75 (1.11-2.75)</td>
<td align="center" valign="middle">2.43</td>
<td align="center" valign="middle">0.015</td>
<td align="center" valign="middle">4.61 (1.44-14.75)</td>
<td align="center" valign="middle">2.58</td>
<td align="center" valign="middle">0.010</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Chinese population</td>
<td align="center" valign="middle">2</td>
<td align="center" valign="middle">526</td>
<td align="center" valign="middle">4.31 (0.51-36.34)</td>
<td align="center" valign="middle">1.34</td>
<td align="center" valign="middle">0.180</td>
<td align="center" valign="middle">2.00 (0.24-16.55)</td>
<td align="center" valign="middle">0.64</td>
<td align="center" valign="middle">0.521</td>
<td align="center" valign="middle">7.91 (1.29-48.44)</td>
<td align="center" valign="middle">2.24</td>
<td align="center" valign="middle">0.025</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Caucasian population</td>
<td align="center" valign="middle">2</td>
<td align="center" valign="middle">1,345</td>
<td align="center" valign="middle">2.37 (0.41-13.87)</td>
<td align="center" valign="middle">0.96</td>
<td align="center" valign="middle">0.337</td>
<td align="center" valign="middle">1.73 (1.09-2.75)</td>
<td align="center" valign="middle">2.33</td>
<td align="center" valign="middle">0.020</td>
<td align="center" valign="middle">2.16 (0.37-12.55)</td>
<td align="center" valign="middle">0.86</td>
<td align="center" valign="middle">0.391</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn><p>OR, odds ratio; CI, confidence interval; <italic>IFITM3</italic>, interferon-induced transmembrane protein 3.</p></fn>
</table-wrap-foot>
</table-wrap>
<table-wrap id="tIII-ETM-25-4-11857" position="float">
<label>Table III</label>
<caption><p>Sensitivity analysis using the one-study remove approach.</p></caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="middle">&#x00A0;</th>
<th align="center" valign="middle" colspan="3">Additive model (CC vs. TT)</th>
<th align="center" valign="middle" colspan="3">Dominant model (CC/CT vs. TT)</th>
<th align="center" valign="middle" colspan="3">Recessive model (CC vs. CT/TT)</th>
</tr>
<tr>
<th align="left" valign="middle">Study omitted</th>
<th align="center" valign="middle">OR (95&#x0025; CI)</th>
<th align="center" valign="middle">Z-value</th>
<th align="center" valign="middle">P-value</th>
<th align="center" valign="middle">OR (95&#x0025; CI)</th>
<th align="center" valign="middle">Z-value</th>
<th align="center" valign="middle">P-value</th>
<th align="center" valign="middle">OR (95&#x0025; CI)</th>
<th align="center" valign="middle">Z-value</th>
<th align="center" valign="middle">P-value</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">Severity</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Overall (5 studies)</td>
<td align="center" valign="middle">1.30 (0.62-2.71)</td>
<td align="center" valign="middle">0.70</td>
<td align="center" valign="middle">0.487</td>
<td align="center" valign="middle">1.02 (0.78-1.34)</td>
<td align="center" valign="middle">0.17</td>
<td align="center" valign="middle">0.862</td>
<td align="center" valign="middle">1.97 (1.06-3.69)</td>
<td align="center" valign="middle">2.13</td>
<td align="center" valign="middle">0.033</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Zhang <italic>et al</italic>, 2020(<xref rid="b10-ETM-25-4-11857" ref-type="bibr">10</xref>)</td>
<td align="center" valign="middle">1.21 (0.50-2.96)</td>
<td align="center" valign="middle">0.42</td>
<td align="center" valign="middle">0.673</td>
<td align="center" valign="middle">1.04 (0.78-1.37)</td>
<td align="center" valign="middle">0.25</td>
<td align="center" valign="middle">0.803</td>
<td align="center" valign="middle">1.67 (0.74-3.79)</td>
<td align="center" valign="middle">1.24</td>
<td align="center" valign="middle">0.217</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Pan <italic>et al</italic>, 2021(<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>)</td>
<td align="center" valign="middle">1.08 (0.44-2.63)</td>
<td align="center" valign="middle">0.17</td>
<td align="center" valign="middle">0.865</td>
<td align="center" valign="middle">1.03 (0.78-1.36)</td>
<td align="center" valign="middle">0.19</td>
<td align="center" valign="middle">0.849</td>
<td align="center" valign="middle">1.58 (0.75-3.35)</td>
<td align="center" valign="middle">1.19</td>
<td align="center" valign="middle">0.233</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Alghamdi <italic>et al</italic>, 2021(<xref rid="b12-ETM-25-4-11857" ref-type="bibr">12</xref>)</td>
<td align="center" valign="middle">1.57 (0.70-3.49)</td>
<td align="center" valign="middle">1.10</td>
<td align="center" valign="middle">0.272</td>
<td align="center" valign="middle">1.10 (0.71-1.71)</td>
<td align="center" valign="middle">0.42</td>
<td align="center" valign="middle">0.674</td>
<td align="center" valign="middle">2.40 (1.23-4.69)</td>
<td align="center" valign="middle">2.57</td>
<td align="center" valign="middle">0.010</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Cuesta-Llavona <italic>et al</italic>, 2021(<xref rid="b13-ETM-25-4-11857" ref-type="bibr">13</xref>)</td>
<td align="center" valign="middle">1.19 (0.54-2.64)</td>
<td align="center" valign="middle">0.44</td>
<td align="center" valign="middle">0.660</td>
<td align="center" valign="middle">0.96 (0.71-1.30)</td>
<td align="center" valign="middle">0.27</td>
<td align="center" valign="middle">0.788</td>
<td align="center" valign="middle">1.95 (1.01-3.78)</td>
<td align="center" valign="middle">1.98</td>
<td align="center" valign="middle">0.048</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Sch&#x00F6;nfelder <italic>et al</italic>, 2021(<xref rid="b14-ETM-25-4-11857" ref-type="bibr">14</xref>)</td>
<td align="center" valign="middle">1.42 (0.66-3.08)</td>
<td align="center" valign="middle">0.90</td>
<td align="center" valign="middle">0.371</td>
<td align="center" valign="middle">1.04 (0.78-1.38)</td>
<td align="center" valign="middle">0.26</td>
<td align="center" valign="middle">0.795</td>
<td align="center" valign="middle">2.18 (1.14-4.19)</td>
<td align="center" valign="middle">2.34</td>
<td align="center" valign="middle">0.019</td>
</tr>
<tr>
<td align="left" valign="middle">Mortality</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
<td align="center" valign="middle">&#x00A0;</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Overall (4 studies)</td>
<td align="center" valign="middle">3.33 (0.85-12.96)</td>
<td align="center" valign="middle">1.73</td>
<td align="center" valign="middle">0.083</td>
<td align="center" valign="middle">1.75 (1.11-2.75)</td>
<td align="center" valign="middle">2.43</td>
<td align="center" valign="middle">0.015</td>
<td align="center" valign="middle">4.61 (1.44-14.75)</td>
<td align="center" valign="middle">2.58</td>
<td align="center" valign="middle">0.010</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Zhang <italic>et al</italic>, 2020(<xref rid="b10-ETM-25-4-11857" ref-type="bibr">10</xref>)</td>
<td align="center" valign="middle">3.47 (0.79-15.28)</td>
<td align="center" valign="middle">1.64</td>
<td align="center" valign="middle">0.101</td>
<td align="center" valign="middle">1.75 (1.11-2.77)</td>
<td align="center" valign="middle">2.40</td>
<td align="center" valign="middle">0.016</td>
<td align="center" valign="middle">4.90 (1.34-17.96)</td>
<td align="center" valign="middle">2.40</td>
<td align="center" valign="middle">0.017</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Pan <italic>et al</italic>, 2021(<xref rid="b11-ETM-25-4-11857" ref-type="bibr">11</xref>)</td>
<td align="center" valign="middle">2.56 (0.54-12.21)</td>
<td align="center" valign="middle">1.18</td>
<td align="center" valign="middle">0.238</td>
<td align="center" valign="middle">1.73 (1.10-2.74)</td>
<td align="center" valign="middle">2.36</td>
<td align="center" valign="middle">0.018</td>
<td align="center" valign="middle">2.76 (0.68-11.11)</td>
<td align="center" valign="middle">1.43</td>
<td align="center" valign="middle">0.154</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Alghamdi <italic>et al</italic>, 2021(<xref rid="b12-ETM-25-4-11857" ref-type="bibr">12</xref>)</td>
<td align="center" valign="middle">4.27 (0.81-22.55)</td>
<td align="center" valign="middle">1.71</td>
<td align="center" valign="middle">0.087</td>
<td align="center" valign="middle">1.74 (0.74-4.06)</td>
<td align="center" valign="middle">1.28</td>
<td align="center" valign="middle">0.202</td>
<td align="center" valign="middle">6.63 (1.61-27.38)</td>
<td align="center" valign="middle">2.61</td>
<td align="center" valign="middle">0.009</td>
</tr>
<tr>
<td align="left" valign="middle">&#x00A0;&#x00A0;&#x00A0;&#x00A0;&#x00A0;Cuesta-Llavona <italic>et al</italic>, 2021(<xref rid="b13-ETM-25-4-11857" ref-type="bibr">13</xref>)</td>
<td align="center" valign="middle">3.12 (0.63-15.48)</td>
<td align="center" valign="middle">1.39</td>
<td align="center" valign="middle">0.163</td>
<td align="center" valign="middle">1.77 (1.06-2.98)</td>
<td align="center" valign="middle">2.17</td>
<td align="center" valign="middle">0.030</td>
<td align="center" valign="middle">4.77 (1.25-18.21)</td>
<td align="center" valign="middle">2.29</td>
<td align="center" valign="middle">0.022</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn><p>OR, odds ratio; CI, confidence interval.</p></fn>
</table-wrap-foot>
</table-wrap>
</floats-group>
</article>
