Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can generate a systemic disease known as coronavirus disease 2019 (COVID-19) (1). COVID-19 has led to the deaths of millions of individuals worldwide, and was thus declared a pandemic in early 2020(2). The most commonly reported symptoms are fever and dyspnea/respiratory distress (3). A number of different risk factors are associated with disease severity, such as smoking, chronic obstructive pulmonary disease (4-6), alcohol consumption (7), co-infections (8,9), metabolic diseases (10-12) and old age (13,14).

Nevertheless, to date, at least to the best of our knowledge, only a limited number of studies have identified SARS-CoV-2 infection in patients with sickle cell disease (SCD) (15,16). SCD is a common genetic disease (17-19) and previous research has failed to identify SCD as a risk factor for COVID-19(15). As has been previously demonstrated, COVID-19 may generate anemia (20) and hypercoagulation (21,22).

Patients with severe COVID-19 infection develop severe lymphopenia (23), increasing the susceptibility of patients for co-infection (24) and also develop multi-organ damage. Nevertheless, following SARS-CoV-2 clearance, the long-term effects of COVID-19 on the hematological and immune response remain unclear.

Due to the lack of knowledge on the immune response of patients with SCD during COVID-19 and the long-term effects of COVID-19(25), the present study describes the hematological alterations of a patient with SCD during hospitalization and at two posterior analyses, namely at 60 and 180 days following hospitalization.

The present study describes the case of a male patient, 42 years of age, previously diagnosed with SCD, homozygous for hemoglobin S, who regularly used folic acid at 5 mg/day. The patient reported a sore throat, body pain and fever (38,5˚C) at 2 days prior to hospitalization. At 1 day prior to hospitalization, he presented with mild dyspnea, a frontal headache and two diarrheal episodes. The patient was diagnosed with COVID-19 on the first hospitalization day, and a chest radiography did not reveal pulmonary ground-glass opacities, with only a small diffuse mosaic attenuation of the pulmonary parenchyma.

The patient was hospitalized in a special ward for COVID-19 patients at the University Hospital (Hospital das Clínicas, Faculty of Medicine, University of São Paulo-HCFMUSP) due to SARS-CoV-2 infection, diagnosed by the nasopharyngeal detection of SARS-CoV-2 RNA (E gene and N gene, with endogenous control with RNAseP), using reverse transcription-polymerase chain reaction (RT-PCR), with a detection limit of 40 copies of viral RNA/reaction (26). The equipment used for RT-PCR was the Abbott m2000sp nucleic acid extractors and the thermal cycler, Abbott m2000rt from Abbott Laboratories Inc. Importantly, the patient did not present any other parasitological, or viral, or bacterial infection during or post-hospitalization, at least to the best of our knowledge. The patient also did not present any comorbidities, such as chronic respiratory diseases, metabolic diseases, or cancer. The laboratory analysis was performed at the Central Laboratory of University Hospital (Central Laboratory Division-HC FMUSP), certified by the College of American Pathologists (CAP), and included the following: Complete blood counts (CBC), liver enzyme levels (alanine aminotransferase and aspartate aminotransferase), bilirubin and fractions (direct and indirect bilirubin), creatinine, C-reactive protein, urea and D-dimer levels, lactate dehydrogenase, total proteins and fractions (albumin and immunoglobulin), erythrocyte sedimentation rate and levels of iron, total iron-binding capacity and iron saturation, in arterial blood collected in K2EDTA collection tubes. Analyses were performed using a Cobas 8100 Automated Workflow Series with a post-analytical unit (Roche Diagnostics).

SARS-CoV-2 S1 IgG was performed by ELISA using the LIAISON^® SARS-CoV-2 S1/S2 IgG kit with proper blank and standard concentration curve according to manufacturer's instructions (DiaSorin). The present study was approved by the Ethics Committee of HCFMUSP on 22/04/2020 (no. 30800520.7.0000.0068-2020). The patient provided written informed consent to participate in the study and for his clinical data to be published.

The day the patient was hospitalized was counted as day 0, the patient cleared SARS-CoV2 infection on day 14, and was discharged on day 16. Laboratory analyses then verified that the patient had a reduced number of erythrocytes, hemoglobin and hematocrit counts during and the post-SARS-CoV-2 clearance (Fig. 1A-C). Importantly, the patient was hospitalized with a low platelet count; however, during the COVID-19 infection, the platelet count normalized and remained within reference levels on day 60 (Fig. 1D). Nevertheless, post-discharge on day 180, the patient presented again with thrombocytopenia (Fig. 1D). At hospitalization, the patient presented a high leukocyte and neutrophil count with lymphopenia (Fig. 1E-G), with a high neutrophil-to-lymphocyte ratio (Fig. 1H). Of note, the eosinophil count peaked on days 60 and 180, and the monocyte count peaked on day 6 (Fig. 1I and J). Urea levels were high at hospitalization, but remained low thereafter (Fig. 1K). The levels of C-reactive protein peaked during hospitalization, and were high upon hospital release, but were low on days 60 and 180 (Fig. 1L). It is noteworthy that the creatinine and D-dimer levels peaked during the COVID-19 infection, but remained high even on days 180 and 60, respectively (Fig. 1M and N). The alanine aminotransferase, aspartate aminotransferase, albumin, globulin and total protein levels were within reference values during and following COVID-19 infection (Fig. 1O-S).

The blood glucose, glycated hemoglobin, potassium, magnesium, sodium, phosphorus, calcium, total bilirubin levels and fractions were maintained within normal levels during and post-hospitalization (data not shown) and to the best of our knowledge, patient was not infected by any bacterial or viral infection during and following COVID-19 hospitalization. On day 180, the platelet count was performed twice, due to excessive platelet aggregation. In addition, on day 180, the patient presented with a high anti-SARS-CoV-2 IgG level >200 UA/ml (data not shown).

The levels of the cardiac function marker, N-terminal pro b-type natriuretic peptide (NT pro-BNP), were 292 pg/ml (reference value, <125 pg/ml) on day 180 (data not shown); however, the pre-COVID-19 levels could not be confirmed. The ferritin levels were high at hospitalization (1,599 ng/ml), and on days 60 (884 ng/ml) and 180 (823 ng/ml), thus suggestive of a severe overload; however, the patient presented with 65 µg/dl of iron at hospitalization, 71 µg/dl on day 60 and 75 µg/dl on day 180 (Fig. 1T). The total iron-binding capacity was below reference values at hospitalization (178 µg/dl), but within the normal range on day 60 (230 µg/dl) and 180 (228 µg/dl) (Fig. 1U). In addition, iron saturation was 31% during COVID-19 infection, 40% on day 60 and 32% on day 180 post-COVID-19 infection (Fig. 1V).

Howell-Jolly corpuscles were found in the patient's blood samples during and post-COVID-19 resolution (days 60 and 180). Reticulocyte frequency was also high during hospitalization and on days 60 and 180 (>11%) (data now shown).

Several risk factors have been associated with COVID-19 prognoses, such as chronic respiratory and inflammatory diseases, metabolic disorders and old age (4,10,27,28). However, to date, little is known about the clinical response of patients with SCD during and post-COVID-19 infection.

The literature presents conflicting results involving SCD and COVID-19. A few reports have identified an association between SCD and an increase in severity or COVID-19-mediated mortality (15,16), particularly in younger individuals (29). Previous studies on COVID-19 in patients with SCD have focused on clinical features (16) and laboratory values at a single time point (15). Several investigations on COVID-19 have also evaluated patients at a single time point (7,30,31). Nevertheless, the longitudinal analysis of clinical data may provide a better overview of the anti-SARS-CoV-2 response of patients (4).

Other reports did not identify SCD as a risk factor for COVID-19 (32-34), or COVID-19 as a risk factor for SCD-mediated vaso-oclusive crisis (35). Nevertheless, patients with SCD have a predisposition to the development of pulmonary hypertension and chronic kidney disease (36).

Importantly, SCD can generate a vascular-endothelial dysfunction, with increased oxidative stress, coagulation and inflammation (37). The pro-inflammatory status in SCD increases neutrophilic and platelet activation (38), and can be further increased during SARS-CoV-2 infection (39). Patients with SCD also present a partially dysfunction in regulatory T-cells (40), which can favor the hyperinflammatory status during COVID-19 infection (41). Other comorbidities, such as tobacco use and diabetes mellitus may also affect the outcome of patients with SCD (15,42). Recently, long COVID-19(43), or long-term COVID-19 sequelae have been extensively investigated (44-46).

The present study described the first report of a COVID-19 disease course in a patient with SCD and the long-term effects of COVID-19, at 2 and 6 months following SARS-CoV-2 infection and hospitalization. The patient presented with classical symptomatic COVID-19, without the need for mechanically assisted ventilation, and was released from the hospital upon SARS-CoV-2 clearance. During hospitalization, the anemia of the patient was further enhanced, probably by the effect of anemia of inflammation (47). COVID-19 patients can develop anemia during the disease course (20) and short-term immune alterations post-COVID-19 have been described (48). The patient described herein fully recovered after 2 weeks, with complete viral clearance, without mechanical ventilation or intensive care. During COVID-19 infection, the patient presented an elevated neutrophil-to-lymphocyte ratio, creatinine levels and C-reactive protein levels (15,28,49). A previous investigation on patients with SCD with COVID-19 infection identified alterations on alanine aminotransferase and direct bilirubin levels (15); however, the present study failed to observe these alterations in the patient described. Nevertheless, to date, to the best of our knowledge, no long-term effects have been investigated. Most importantly at 2 and 6 months following hospital discharge, the patient still presented alterations in certain inflammatory markers, mainly creatinine and D-dimer levels, and an elevated reticulocyte frequency (>11%). Elevated D-dimer levels have been described after COVID-19 in up to 25% of recovered patients and may predispose individuals post-COVID-19 to coagulatory disorders (45). D-dimer levels are usually elevated during a SCD crisis (50); however, the patient described herein did not report any health issue post-COVID-19 infection. A dysregulation in serum creatinine levels has also been described in patients following COVID-19 infection (44). Upon investigation, it was confirmed that during a previous hospitalization in 2017, patient reticulocyte frequency was much lower (<6%), indicating that this further elevation may be a result of COVID-19 infection. A previous alteration in red blood cells or an increased reticulocyte frequency during COVID-19 have been reported; however, recovered patients did not present long-term alteration (51).

In conclusion, the present study described the case of a patient with SCD with COVID-19. The patient presented a complete viral clearance at 2 weeks following hospitalization in the general ward. To the best of our knowledge, this is the first report demonstrating the long-term effect of COVID-19 in a patient with SCD. The patient presented alterations in reticulocyte count, creatinine and D-dimer levels. Due to the nature of case reports, further in-depth investigations on the long-term effects of COVID-19 sequelae are necessary.