[Comparative Analyses of IgA Antibody Response of Non-COVID-19 Infected People Over 60 Years Old Following CoronaVac and Pfizer-BioNTech COVID-19 Vaccination].

The formation rate, magnitude, and duration of the antibody-mediated humoral immune response that develops against different viral proteins of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are considered important in vaccine success. It is known that the response to vaccinations decreases due to immunosenescence in older adults. This study was aimed to investigate the levels of serum IgA response at 1st and 3rd month after vaccination of people over 60 years old who were immunized with CoronaVac and Pfizer-BioNTech. A total of 35 people living in the North Cyprus who have not previously had COVID-19 infection were included in the study. After the 2nd dose of vaccination, serum IgA levels were measured after the 1st and 3rd month with the anti-SARS-CoV-2 IgA (Euroimmun, Lubeck, Germany) kit. The statistical significance was determined as 0.05 in the whole study. SPSS and GraphPad Prism software were used for calculations, analyses and graphs. The possible effect of demographic variables on serum IgA level was compared between the vaccine groups and it was found that there was no statistically significant difference between them. For the IgA titer-positive individuals who had been vaccinated with the Pfizer-BioNTech vaccine, for both 1st and 3rd months were observed to be higher than CoronaVac vaccinated IgA titer-positive individuals. In individuals who received the CoronaVac vaccine, there was a statistically significant change in serum IgA levels between 1st and 3rd months, but there was no statistically significant change in the Pfizer-BioNTech vaccine administered group. When the Pfizer/BioNTech and CoronaVac vaccines were compared with each other in terms of serum IgA antibody titers, it was found that the mean serum IgA levels of the individuals in the Pfizer/BioNTech group were statistically higher at the 1st and 3rd months than the CoronaVac group. Serum IgA titers in both vaccine groups were statistically significantly decreased from 1st month to 3rd month. This study showed that the Pfizer/BioNTech vaccine induced higher SARS-CoV-2 specific serum IgA antibodies than the CoronaVac vaccine and remained seropositive for a longer time in individuals aged 60 years and older. It is believed that the serum IgA levels that were determined may not reflect the serum IgA levels. However, these findings support the studies in other literature, showing that the Pfizer-BioNTech mRNA vaccine induces higher SARS-CoV-2 specific serum IgA antibodies than the inactive CoronaVac vaccine and that it remains seropositive for a longer period of time. This study is important as it is the first study to compare the SARS-CoV-2 IgA antibody responses of individuals over 60 years of age in the Turkish Republic of Northern Cyprus in two different vaccine groups.