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Observational Study
. 2022 Sep:122:99-106.
doi: 10.1016/j.ijid.2022.05.007. Epub 2022 May 11.

Evaluation of long-term antibody kinetics in healthcare workers vaccinated with inactivated COVID-19 Vero cell vaccine (CoronaVac), a propensity score-matched observational study

Yesim Yildiz  1 , Hasan Selcuk Ozger  2 , Esin Senol  2 , Resul Karakus  3 , Merve Buyukkoruk  2 , Fatma Betul Altin  2 , Fatma Zehra Ozcan  2 , Melek Yaman  3 , Nihan Oruklu  3 , Aysegul Atak Yucel  3 , Emin Umit Bagriacik  3
Affiliations
Observational Study

Evaluation of long-term antibody kinetics in healthcare workers vaccinated with inactivated COVID-19 Vero cell vaccine (CoronaVac), a propensity score-matched observational study

Yesim Yildiz et al. Int J Infect Dis. 2022 Sep.

Abstract

Objectives: This study aimed to evaluate the long-term antibody kinetics after vaccinating with an inactivated COVID-19 Vero cell vaccine (CoronaVac) in healthcare workers (HCWs) at a single center in Turkey.

Methods: For this prospective observational study, Chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) were used for the determination of binding antibodies (bAb) and neutralizing antibodies (nAb), respectively. Antibody kinetics were compared for the potential influencing factors, and propensity score analysis was performed to match the subcohort for age.

Results: Early bAb and nAb response was achieved in all 343 participants. Titers of bAbs against SARS-CoV-2 on 42 days post-vaccination (dpv) were higher in HCWs who were aged <40 years and who had a history of COVID-19. SARS-CoV-2 bAb levels in HCWs on days 42 (n = 97), 90 (n = 97), and 180 (n = 97) were 175 IU/ml (3.9-250), 107 IU/ml (2.4-250), and 66.1 IU/ml (2.57-250), respectively (p<0.001). SARS-CoV-2 bAb (p<0.001) and nAb (p<0.001) titers decreased significantly over time. There was a high negative correlation between SARS-CoV-2 antibody titers and inverse optic density of nAb responses (Pearson correlation coefficient: -0.738, p<0.001).

Conclusions: When the antibody responses were compared, it was seen that the vaccine immunogenicity was better in those who had prior COVID-19 history and were aged <40 years. In the course of time, it was determined that there was a significant decrease in bAb and nAb responses after the 90th day. These results may guide approval decisions for booster COVID-19 vaccines.

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Conflict of interest statement

Declaration of competing interest The authors have no competing interests to declare.

Figures

Figure 1
Figure 1
Flowchart of the study.
Figure 2
Figure 2
Timeline of the vaccination and sampling of HCWs.
Figure 3
Figure 3
The change of geometric mean titers (GMTs) of binding antibodies (bAbs) and percentage of neutralizing antibodies (nAbs) in 97 healthcare workers (HCWs) on 42, 90, and 180 days post-vaccination (dpv).
Figure 4
Figure 4
Correlation between binding antibody titers against SARS-CoV-2 and neutralizing antibody responses according to age .
Figure 5
Figure 5
Correlation between binding antibody titers against SARS-CoV-2 and neutralizing antibody responses according to COVID-19 history .
See this image and copyright information in PMC

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