Dynamics of antibody response to CoronaVac vaccine

Abstract

CoronaVac was the first vaccine approved in Brazil for use in healthcare workers (HCWs). However, there is limited information about it, with little long-term evidence on post-vaccination antibody persistence. This study evaluated the antibody response to SARS-CoV-2 in 1237 HCWs after the first (1D), second dose (2D), and 6 months postvaccination (6mA2D) with CoronaVac. The seropositivity was 88% at 1D, increasing to 99.8% at 2D, but decreasing to 97.9% at 6mA2D, which was also observed at the analyzed antibody levels. Interestingly, the levels in females were higher than males, and we found a positive correlation with previous SARS-CoV-2 infection. Participants with comorbidities had lower levels suggesting the need to monitor for a potential booster dose. Our findings suggest that CoronaVac induced a robust antibody response that wanes significantly over time. Further longitudinal studies are needed to identify whether the antibodies will decline or plateau at a lower level.

Keywords: CoronaVac; IgG antibody; SARS-CoV-2; healthcare workers; serology.

Conflict of interest statement

The authors declare no conflict of interest.

© 2022 Wiley Periodicals LLC.

Figures

Figure 1

Anti‐S IgG levels in healthcare workers vaccinated with Coronavac. The evaluation was performed after 28 days of the first dose (1D), 28 days of the second dose (2D), and 6 months after the second dose of CoronaVac (6mA2D). Data were expressed by the concentration AU/ml for median values and the comparisons were performed with the Kruskal–Wallis test and Dunn's multiple testing correction

Figure 2

Anti‐S IgG levels by female and male individuals (A), and by age group (B). The evaluation was performed after 28 days of the first dose (1D), 28 days of the second dose (2D), and 6 months after the second dose with CoronaVac (6mA2D). Data were expressed by the concentration AU/ml for median values. The comparisons between groups of different time points were performed with the Kruskall–Wallis test and Dunn's multiple testing correction, and the comparisons between groups of the same time point were performed with test t and Mann–Whitney; p‐values < 0.0001 are reported as exact numbers

Figure 3

Anti‐S IgG levels in healthcare workers vaccinated with Coronavac, according to previous COVID‐19 infection. The quantitative assessment of IgG was measured after 28 days of the first dose (1D), 28 days of the second dose (2D), and 6 months after the second dose with CoronaVac (6mA2D). The groups were divided in positive RT‐PCR and negative RT‐PCR before vaccination. Data were expressed by the concentration AU/ml for median values. The comparisons between groups of different time points were performed with the Kruskal–Wallis test and Dunn's multiple testing correction, and the comparisons between groups of the same time point were performed with test t and Mann–Whitney; p‐values < 0.0001 are reported as exact numbers

Figure 4

Anti‐S IgG in healthcare workers according to comorbidity (A) and autoimmune disease (B). The evaluation was performed after 28 days of the first dose (1D), 28 days of the second dose (2D), and 6 months after the second dose with CoronaVac (6mA2D). Data were expressed by the concentration AU/ml for median values. The comparisons between groups of different time points were performed with the Kruskal–Wallis test and Dunn's multiple testing correction, and the comparisons between groups of the same time point were performed with test t and Mann–Whitney; p‐values < 0.0001 are reported as exact numbers