Monitoring SARS CoV-2 antibodies positivity in healthcare workers after inactivated CoronaVac® vaccine

• Published in: Germs (Bucureşti) Vol. 12; no. 4; pp. 507 - 518
• Main Authors: Demir, Melek, Çalışkan, Ahmet, Kaleli, İlknur, Dönmez, Büşra, Er, Hatice, Ergin, Çağrı
• Format: Journal Article
• Language: English
• Published: Bucharest Asociatia pentru Cresterea Vizibilitatii Cercetarii Stiintifice (ACVCS) 01.12.2022; European HIV/AIDS and Infectious Diseases Academy
• Subjects: Antibodies; Asymptomatic; Coronaviruses; COVID-19 vaccines; Disease transmission; Drug dosages; Drug therapy; Emergency medical care; Health aspects; Hospitalization; Immune system; Immunoassay; Infections; Infectious diseases; Investigations; Medical personnel; Pneumonia; Questionnaires; Severe acute respiratory syndrome coronavirus 2; Testing; China; Ireland; Turkey
• ISSN: 2248-2997; 2248-2997
• DOI: 10.18683/germs.2022.1356

Introduction In this study, we aimed to monitor anti-spike and anti-nucleocapsid antibodies positivity in healthcare workers (HCWs) vaccinated with two doses of inactivated CoronaVac[R] (Sinovac, China) vaccine. Methods Overall, 242 volunteer HCWs were included. Of the participants, 193 were HCWs without history of prior documented COVID-19 (Group 1), while 49 had history of prior documented COVID-19 before vaccination (Group 2). The participants were followed up for SARS-CoV-2 antibodies positivity at four different blood sampling time points (immediately before the second vaccine dose and at the 1st, 3rd months and 141-150 days after the second dose). We investigated the serum IgG class antibodies against SARS-CoV-2 RBD region and IgG class antibodies against SARS-CoV-2 nucleocapsid antigen by chemiluminescent microparticle immunoassay (CMIA) method using commercial kits. Results We found positive serum anti-RBD IgG antibody in 76.4% of the participants (71% in Group 1; 98% in Group 2) 28 days after the first dose. When the antibody levels of the groups were compared at the four blood sampling time points, Group 2 anti-RBD IgG levels were found to be significantly higher than those in Group 1 at all follow-up time points. Although anti-RBD IgG positivity persisted in 95.6% of all participants in the last blood sampling time point, a significant decrease was observed in antibody levels compared to the previous blood sampling time point. Anti-nucleocapsid IgG antibody was positive in 12 (6.2%) of participants in Group 1 and 32 (65.3%) in Group 2 at day 28 after the first dose. At the fourth blood sampling time point, anti-nucleocapsid antibodies were found to be positive in a total of 20 (9.7%) subjects, 10 (6.1%) in Group 1 and 10 (23.8%) in Group 2. Conclusions In this study, it was determined that serum antibody levels decreased in both groups after the third month after the second dose in HCWs vaccinated with CoronaVac[R] vaccine. Keywords COVID-19, SARS-CoV-2, vaccination, CoronaVac[R], healthcare workers.