Study of the state of humoral immunity to COVID-19 in Arkhangelsk residents

The COVID-19 pandemic caused by SARS-CoV-2 has affected healthcare, society and the economy in all countries, including Russia. Several vaccines have been created as the method for COVID-19 prevention. One of the most widespread vaccines in Russia, which has received international recognition, is the Gam-COVID-Vac (Sputnik V) vaccine and its variant Sputnik Light, which represents its first component. This vaccine, like similar vaccines in many countries, was used during the pandemic. The purpose of this work is to study the humoral immunity status of Arkhangelsk city residents and the effect of vaccination on them. Adult residents of Arkhangelsk [N = 281] were enrolled in the randomized study. Samples from vaccinated people and the control group were collected for the study in October 2022.The median from the time of last vaccination/booster to sample collection was 10 months. The samples were tested for the level of IgG to the receptor-binding domain of the SARS-CoV-2 S protein. The work assessed the humoral immunity status among residents of Arkhangelsk. It was shown that in October 2022 high IgG values were recorded among the people in the studied groups, most likely caused by contact with the SARS-CoV-2 virus. The humoral immunity status of unvaccinated residents, for those who have had COVID-19 and those who have not, is described; a significant increase in the level of IgG among those vaccinated compared to unvaccinated people is shown, despite the fact that the average time after vaccination was more than 10 months. A comparative analysis of IgG levels among different age groups was carried out. The study found no difference in post-vaccination antibody levels among people over 65 years old compared to younger age groups. Also there were no statistically significant differences in antibody levels among unvaccinated people over 65 in respect to younger age groups.