TY - JOUR AB - Soon after the beginning of the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) pandemic in December, 2019, numerous research teams, assisted by vast capital investments, achieved vaccine development in a fraction of time. However, almost 8 months following the initiation of the European vaccination programme, the need for prospective monitoring of the vaccine‑induced immune response, its determinants and related side‑effects remains a priority. The present study aimed to quantify the immune response following full vaccination with the BNT162b2 coronavirus disease 2019 (COVID‑19) mRNA vaccine by measuring the levels of immunoglobulin G (IgG) titers in healthcare professionals. Moreover, common side‑effects and factors associated with IgG titers were identified. For this purpose, blood samples from 517 individuals were obtained and analysed. Blood sampling was performed at a mean period of 69.0±23.5 days following the second dose of the vaccine. SARS‑CoV‑2 IgG titers had an overall mean value of 4.23±2.76. Females had higher titers than males (4.44±2.70 and 3.89 ±2.84, respectively; P=0.007), while non‑smokers had higher titers than smokers (4.48±2.79 and 3.80±2.64, respectively; P=0.003). An older age was also associated with lower antibody titers (P<0.001). Moreover, the six most prevalent adverse effects were pain at the injection site (72.1%), generalized fatigue (40.5%), malaise (36.3%), myalgia (31,0%), headache (25.8%) and dizziness/weakness (21.6%). The present study demonstrated that the immune response after receiving the BNT162b2 COVID‑19 mRNA vaccine is dependent on various modifiable and non‑modifiable factors. Overall, the findings of the present study highlight two key aspects of the vaccination programs: First, the need for prospective immunosurveillance studies in order to estimate the duration of immunity, and second, the need to identify those individuals who are at a greater risk of developing low IgG titers in order to evaluate the need for a third dose of the vaccine. AD - Laboratory of Toxicology, Medical School, University of Crete, 71003 Heraklion, Greece Department of General Surgery, Venizeleion General Hospital, 71409 Heraklion, Greece Laboratory of Molecular Biology and Immunology, Department of Pharmacy, University of Patras, 26500 Rio‑Patras, Greece Department of Emergency Medicine, Venizeleion General Hospital, 71409 Heraklion, Greece Department of Neonatology and Neonatal Intensive Care Unit, University Hospital of Heraklion, 71500 Heraklion, Greece Department of Internal Medicine, Venizeleion General Hospital, 71409 Heraklion, Greece Research Group of Clinical Pharmacology and Pharmacogenomics, Faculty of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, 15772 Athens, Greece Section of Molecular Pathology and Human Genetics, Department of Internal Medicine, School of Medicine, University of Crete, 71003 Heraklion, Greece Department of Cardiothoracic Surgery, University Hospital of Heraklion, 71500 Heraklion, Greece Emergency Department, Venizeleion General Hospital, 71409 Heraklion, Greece Laboratory of Clinical Virology, Medical School, University of Crete, 71003 Heraklion, Greece AU - Tsatsakis,Aristidis AU - Vakonaki,Elena AU - Tzatzarakis,Manolis AU - Flamourakis,Matthaios AU - Nikolouzakis,Taxiarchis,Konstantinos AU - Poulas,Konstantinos AU - Papazoglou,Georgios AU - Hatzidaki,Eleftheria AU - Papanikolaou,Nikolas,C. AU - Drakoulis,Nikolaos AU - Iliaki,Evangelia AU - Goulielmos,Georgios,N. AU - Kallionakis,Manolis AU - Lazopoulos,Georgios AU - Kteniadakis,Stelios AU - Alegkakis,Athanasios AU - Farsalinos,Konstantinos AU - Spandidos,Demetrios,A. DA - 2021/11/01 DO - 10.3892/ijmm.2021.5033 IS - 5 JO - Int J Mol Med KW - antibody titers SARS‑CoV‑2 COVID‑19 vaccination BNT162b2 COVID‑19 mRNA IgG PY - 2021 SN - 1107-3756 1791-244X SP - 200 ST - Immune response (IgG) following full inoculation with BNT162b2 COVID‑19 mRNA among healthcare professionals T2 - International Journal of Molecular Medicine TI - Immune response (IgG) following full inoculation with BNT162b2 COVID‑19 mRNA among healthcare professionals UR - https://doi.org/10.3892/ijmm.2021.5033 VL - 48 ER -