Waning of SARS-CoV-2 Antibody levels response to inactivated cellular vaccine over 6 months among healthcare workers

Abstract

Background Health Care workers (HCW) are an important group affected by this pandemic and COVID-19 has presented substantial challenges for health professionals and health systems in many countries. The Brazilian vaccination plan implemented in October, so that third dose for HCW. However, the persistence of CoronaVac vaccine-induced immunity is unknown, and immunogenicity according to age cohorts may differ among individuals. Objective Evaluate the post vaccination immune humoral response and the relationship between post-vaccination seropositivity rates and demographic data among Healthcare Workers over 6 months after CoronaVac immunization. Methods A cross section study including Healthcare professionals vaccinated with CoronaVac for 6 months or more. The study was carried with the analysis of post-vaccination serological test to assess the levels of humoral response after vaccination. Results 329 participants were included. Among them, 76% were female. Overall, 18.5% were positive quantitative titles (IQR 42.87-125.5) and the negative group was 80%, quantitative titles (IQR 5.50-13.92). Conclusion It was possible to identify a group with positive quantitative titles in serological test for IgG antibody against the SARS-CoV-2. Further investigation is required to determine the durability of post-vaccination antibodies and how serological tests can be determine the ideal timing of vaccine booster doses.

Immunogenicity of BNT162b2, BBIBP-CorV, Gam-COVID-Vac and ChAdOx1 nCoV-19 Vaccines Six Months after the Second Dose: A Longitudinal Prospective Study

“…Even though this issue was beyond the scope of the current study, we found that the majority of recipients vaccinated with BNT162b2, Gam-COVID-Vac and ChAdOx1 nCoV-19 remained seropositive to SARS-CoV-2 virus at 6 months, in comparison to 40% of those vaccinated with BBIBP-CorV, with no significant differences regarding sex. A lower percentage of seropositivity at 6 months after vaccination with another inactivated SARS-CoV-2 vaccine (CoronaVac) was previously demonstrated in a similar study by Taminato et al, where only 20% of participants were seropositive for more than 6 months [ 36 ]. Of note, measuring just the Ab response against S protein, especially after being vaccinated with the whole-virus vaccines, such as BBIBP-CorV, might not be enough to evaluate the complete immune response, since the production of other Abs against different SARS-CoV-2 antigens is also induced [ 23 ].…”

“…Thus, the assessment of post-vaccination titers/levels can help to better understand vaccine’s long-term efficacy and improve current vaccination strategies [ 34 ]. Indeed, serious concerns have been raised about the longevity of post-vaccination immunity, especially with the occurrence of new COVID-19 cases in countries where a high vaccination rate was reached [ 35 , 36 ]. In the longitudinal part of our study, we noticed a significant decline in Ab levels between two time points, at the 28th day and at 6 months, following the application of the second dose of BNT162b2, BBIBP-CorV, and Gam-COVID-Vac.…”

“…An Italian study evaluated anti S-RBD IgG levels in 2248 vaccinated subjects and reported higher initial levels in women in comparison to men, although at 72 days after the first measurement this difference was lost [ 53 ]. Similarly, a study conducted in Brazil among HCWs vaccinated with inactivated vaccine (CoronaVac–Sinovac) did not find any difference measured at 6 months or even more, between different age groups and sexes [ 36 ]. On the other hand, a recent meta-analysis investigated the efficacy of BNT162b2, Gam-COVID-Vac, mRNA-1273-Moderna and Ad26.COV2.S-Johnson&Johnson/Janssen, showed a significantly increased efficacy in men compared to women [ 54 ].…”