Study of protective antibodies after Sinopharm anti-SARS-CoV2 (BBIBP-CorV) vaccine

Abstract

Background: Following the declaration of the coronavirus as a pandemic by the World Health Organization (WHO), a total of 183 distinct vaccine candidates have undergone clinical testing till March 2023. Since February 23, 2021, Mongolia has administered four different vaccines: Pfizer/BioNTech (BNT162b2), AstraZeneca (ChAdOx1-S), Sinopharm (BBIBP-CorV), and Sputnik V (Gam-COVID-Vac). As of October 14, 2022, the second dosage of the vaccine has been administered to a total of 2,183,894 individuals. Continued investigation is being conducted on these vaccinations. In this study, we aimed to investigate the immunogenicity of Sinopharm’s Covid-19 vaccine, known as BBIBP-CorV. Aim: To investigate the parameters that influence the antibody response following Sinopharm (BBIBP-CorV) vaccination against Covid-19 infection in various population groups. Materials and Methods: The study included a cohort of 583 individuals who got both the initial and booster doses of the Sinopharm (BBIBP-CorV) vaccination. Serum samples were analysed for Immunoglobulin G (IgG) antibodies targeting the S protein of the SARS-CoV-2 virus. The initial analysis was conducted before administering the first dose of the COVID-19 vaccine, and a subsequent test was performed between days 21-28 after the second vaccination dosage. Results: A total of 213 individuals (36.5%) who were men and 370 individuals (63.5%) who were women, ranging in age from 19 to 86, took part in the study. The average age of the participants was 38.1±10.7 (37.0), and 52.9% of the respondents were between the ages of 30 and 49. Out of the total responses, 80.6% (470) exhibited adequate levels of antibody titers, but 19.4% (113) did not exhibit any detectable antibodies. The geometric mean titer (GMT) of the anti-SARS-CoV-2 RBD-IgG antibody was 0.7±0.9 ng/mL before to vaccination. However, after receiving the second dose, the GMT significantly rose to 17.2±1.2 ng/mL. Upon examining the age group, it was noted that individuals under the age of 40 exhibit robust synthesis of protective antibodies, but antibody production diminishes as age increases. The antibody response to the Sinopharm (BBIBP-CorV) vaccine is more pronounced among individuals residing in rural regions compared to those living in Ulaanbaatar city. Nevertheless, we found it intriguing that the antibody response was comparatively diminished in Bulgan and Dornod provinces in contrast to Darkhan-Uul and Orkhon provinces. Conclusions: 1. Following the administration of the second dosage of the Sinopharm vaccine, also known as BBIBP-CorV, a significant proportion of individuals (80.6%) exhibited the presence of protective antibodies during a period of 21-28 days. The antibody response diminishes with advancing age. 2. Antibody titers after the 2nd dose of Sinopharm (BBIBP-CorV) vaccine against Covid-19 infection were not related to the age and gender of the participants, as well as the occupational risk.