Antibody responses after COVID-19 vaccination: a cross sectional study among the Bangladeshi population

The effectiveness of immunizations against coronavirus disease 2019 (COVID-19) varies greatly from one vaccine to the next. The same dose of the same vaccines will stimulate an individual's immune system to varying degrees in different persons because of a number of genetic and physiological variables. The study aimed to investigate the differences in antibody responses between COVID-19 vaccine recipients and nonrecipients. Data from 187 adult respondents were collected between November 2021 to February 2022, using a semi-structured and standardized questionnaire. For qualitative measurement of circulating neutralizing antibodies, fluorescent immunoassay was used. Whole genome sequencing of SARS CoV-2 isolates was done confirming the variants. The study found a substantial correlation between demographic factors and vaccine acceptance rates. Neutralizing antibody (NAbs) titer was higher in male participants than female participants (P = 0.024). Young and healthy participants (P = 0.505) exhibited greater antibody titers than participants with increased age or comorbid condition (P = 0.835). In comparison to other groups, increased level of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) NAbs for V1 (B.1.1.7 alpha-Kent) and V2 (B.1.351 beta-South African) were found in 82.35 and 64.71% of the vaccinated and previously infected individuals. Moreover, Moderna showed the highest mean Nab percentage of inhibition (%) antibody levels specific for V1 variant: 89.62% [95% confidence interval (CI) 76.07–103.17] whereas Pfizer BioNTech displayed the same for V2 variant: 87.20% (95% CI 34.09–140.34). This study signifies on the integration of antibody tests in vaccination programs in the healthcare system for maximizing benefit, particularly with the emergence of new SARS-CoV-2 variants over time.