Variety of Antibody Responses to BNT162b2 and BBIBP-CorV Vaccinations Against COVID-19 Infections in Baghdad and Fallujah, Iraq

Abstract

The huge impact of COVID-19 worldwide led to the rapid development of vaccines with inadequate data about its longevity, effectivity, and safety. This study aims to evaluate the effectiveness and safety of COVID-19 vaccines available in Iraq and to measure longevity of created antibody response among different time points of both Pfizer-BioNTech and Sinopharm vaccines in Baghdad and Fallujah, Iraq. A two-axis method was used: the first was cross sectional study on the vaccination state for COVID-19 in Baghdad and Fallujah, using an online survey contained questions about city, vaccine type, side effect, pre and post infections, and chronic diseases. The second part involved a prospective observational study of the vaccine’s immunological effectiveness and stability in 60 serum samples from completely vaccinated individuals (second dose) of Pfizer or Sinopharm along different time points (1 - 6 months) by measuring the SARS-CoV-2 Anti-RBD-IgG concentration and evaluating its correlation with pre-infection with COVID-19. Among different types of vaccines available in Iraq, people in Baghdad and Fallujah preferred Pfizer vaccine over other available types, particularly those with chronic diseases. No statistically significant difference was noticed between IgG concentrations at different points of time, IgG concentrations in Pfizer vaccinated individuals were more elevated than Sinopharm, and all of Pfizer vaccinated people showed positive results. Our study established a synergistic impact between recent COVID-19 infection and vaccination, leading to increased levels of IgG antibodies, notably in individuals who received the Pfizer vaccine. Additionally, our findings demonstrate that IgG concentrations remained stable in vaccinated individuals even six months after completing the vaccination with second dose.