Longitudinal Randomized Cohort Study of SARS-CoV-2 Antibody Seroprevalence in the St. Petersburg Population

Abstract

Introduction. Since the detection of the first COVID-19 patient, 2 years have passed, during which more than 287,862,000 people have fallen ill globally, of which about 1.9% died. The implementation of SARS-CoV-2 control programs required efforts from almost all countries. An important direction in the fight against COVID-19 has been the formation of herd immunity, the main tool for managing the pandemic. Study goal. The aim of the study was to assess the seroprevalence of antibodies (Abs) to SARS-CoV-2 nucleocapsid (Nc) and receptor binding domain (RBD) in the St. Petersburg population during the COVID-19 pandemic. Materials and methods. A longitudinal cohort randomized monitoring study of Ab seroprevalence (SARS-CoV-2 Nc, RBD) was organized and conducted according to a unified methodology developed by Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute. For this purpose, a cohort was formed of 1000 volunteers who participated in all five stages of seromonitoring. The cohort was divided into seven age groups: 1–17; 18–29; 30–39; 40–49; 50–59; 60–69; 70; and older (70+) years. Seropositivity levels (Nc, RBD) were assessed by quantitative and qualitative enzyme immunoassays. During the second year of monitoring, some volunteers were vaccinated with the GamCOVIDVac (84%) or EpiVacCorona (11.6%) vaccines approved in Russia. Statistical processing was carried out using Excel 2010. Confidence intervals for shares and percentages (95% CI) were calculated using the method of A. Wald and J. Wolfowitz with adjustment (A. Agresti, B.A. Coull). The statistical significance of differences was calculated by z-test, using the appropriate online calculator (p < 0.05) unless indicated. Results. There was a trend toward an increase in Nc seropositivity in stages 1–3 of seromonitoring, with a decrease in stages 4–5 among children and adults. The share of RBD seropositive steadily increased during all five stages of seromonitoring. The most frequent finding was low anti-RBD Abs levels (22.6–220 BAU/mL). High Ab levels were recorded statistically significantly less frequently. Asymptomatic forms were observed in 84–88% of SARS-CoV-2 seropositive volunteers. By the fifth stage of monitoring, this indicator significantly decreased to 69.8% (95% CI: 66.1–73.4). The monitoring revealed a statistically significant increase in anti-RBD Abs alongside a statistically significant decrease in the proportion of Nc seropositives. This dynamic was especially characteristic of persons vaccinated with GamCOVIDVac. Conclusion. Prior to the use of specific vaccines, a seroprevalence of anti-Nc Abs was noted. After the introduction of the GamCOVIDVac vaccine in adults, a decrease in the level of anti-Nc Abs was noted due to an increase in the proportion of RBD seropositive persons.

Patterns in the development of collective immunity to SARS-CoV-2 during the COVID-19 pandemic

“…Subsequently (2020-2021), following increased COVID-19 incidence, seroprevalence in the Russian population steadily increased, exceeding 70% in December 2021. At the same time, fluctuations in indicators across Russian regions gradually leveled off [5,7,14].…”

“…At the beginning of the local epidemic in May 2020, Rospotrebnadzor developed a multi-stage program for seromonitoring of the population's immunity to SARS-CoV-2. It was implemented in 2020-2021 in Russia [5,7,14]. Since 2021-2023, neighboring countries have participated in a partnership program (Armenia, Belarus, Kyrgyzstan, Tajikistan) [6,10,11,12].…”

“…The total number of volunteers was 74,158 people and was representative of the total Russian population. The study was conducted in 2020-2021 in 5 stages, with an interval of 3-9 months (Figure 1) [5,7,14]. In Armenia, Belarus, Kyrgyzstan and Tajikistan, 32,128 volunteers were examined for population dynamics in 2021-2023; from 2 to 4 stages were carried out in each country (Figure 2).…”

SARS-CoV-2 in Mozambican primary school-aged children at Maputo City and Province: a cross-sectional study from a low-income country

“…Global prevalence data indicate that SARS-CoV-2 infection in children and adolescents has increased due to the increased circulation of Delta and Omicron variants and increased vaccination coverage against COVID-19 among adults [ 25 ]. This high seroprevalence of SARS-CoV-2 indicates that many children were exposed to the virus and developed antibodies that can contribute to the herd immunity and reduce the transmission of the virus in the community and school and reducing the probability of occurrence of outbreaks that can overload the health system [ 26 , 27 ].…”

Characterizing A “N-CoV-2-IgG PS” diagnostic kit to quantify SARS-CoV-2 nucleocapsid protein-specific human IgG antibodies

“…Таким образом, результаты проведенного исследования продемонстрировали наличие хорошей корреляционной связи между N-белоксвязывающими антителами и сопоставимости разработанного нами набора с тестом нейтра-лизации вируса SARS-CoV-2. Проверка между тестовой согласованностью свидетельствовала об информативности и эффективности разработанного набора, что подтвердило его потенциал для проведения скрининга IgG антител у лиц, переболевших COVID-19, и для использования его в масштабных популяционных исследованиях [2,10,12] для оценки серопревалентности к COVID-19 в разных группах населения.…”