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

Melek Demir; Ahmet Çalışkan; İlknur Kaleli; Büşra Dönmez; Hatice Er; Çağrı Ergin

doi:10.18683/germs.2022.1356

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

Germs. 2022 Dec 31;12(4):507-518. doi: 10.18683/germs.2022.1356. eCollection 2022 Dec.

Authors

Melek Demir¹, Ahmet Çalışkan², İlknur Kaleli², Büşra Dönmez², Hatice Er², Çağrı Ergin²

Affiliations

¹ MD, PhD, Pamukkale University, Medical Faculty, Department of Medical Microbiology, Denizli, 20070, Turkey.
² MD, Pamukkale University, Medical Faculty, Department of Medical Microbiology, Denizli, 20070, Turkey.

Abstract

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^® (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 1^st, 3^rd 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^® vaccine.

Keywords: COVID-19; SARS-CoV-2; healthcare workers; vaccination, CoronaVac®.

GERMS.