HERD IMMUNITY TO SARS-CoV-2 AMONG ADOLESCENT STUDENTS OF THE RUSSIAN DEFENSE MINISTRY COLLEGES OF THE CITY OF SAINT PETERSBURG

ABSTRACT

The morbidity of the new coronavirus infection (COVID-19) in the Russian Armed Forces is decreasing thanks to the sanitary and preventive anti-epidemic measures, the most effective of which is mass vaccination. The purpose of this research was to study the peculiarities of the formation of herd immunity among adolescent students of the Russian Ministry of Defense (MoD) colleges against the background of the COVID-19 epidemic. Materials and methods of the research according to the epidemic indications, a two-stage seroepidemiological multicenter prospective study of herd immunity to SARS-CoV-2 was carried out in Dec. 2021 - May 2022, against the background of vaccination, among adolescent students of the Russian Defense Ministry colleges. 515 adolescents aged 11 to 17 years old (median age 13 [12;15] years old) from the two Russian MoD schools located in the city of Saint Petersburg, of which 292 (57%) girls and 223 (43%) boys, were involved in the study. The adolescents were divided into groups based on gender and previous COVID-19 illness e.g., those who already had COVID-19 and those who had not prior to the study. In the second stage of the study the number of samples from boys and girls decreased by 74.3% and 34.4%, respectively, due to the lack of parents' consent to the vaccination. The assessment of the immunity intensity was carried out using the Anti-SARS-CoV-2 IgG levels in blood serum by enzyme-linked immunosorbent assay (ELISA). Result(s) the initially high levels of seroprevalence to SARS-CoV-2 were established among both girls and boys (90.4% and 91.5%, respectively, p=0.09) that indicated a latent course of the epidemic process in the studied groups of teenagers. In adolescent girls and boys vaccinated against the background of a previous COVID-19 illness, the combined immunity is formed in 62.3% and 68.1%, respectively (p=0.11). Conclusion(s) the epidemic process of COVID-19 tends to be latent in organized adolescent groups, being realized in inapparent forms of the infection. Those adolescents who've been vaccinated after COVID-19 illness develop the immunity with positive seroconversion dynamics. Copyright © 2022, Pediatria Ltd. All rights reserved.