Seroprevalence of SARS-CoV-2 antibodies in Saint Petersburg, Russia: a population-based study

Abstract

Properly conducted serological survey can help determine infection disease true spread. This study aims to estimate the seroprevalence of SARS-CoV-2 antibodies in Saint Petersburg, Russia accounting for non-response bias. A sample of adults was recruited with random digit dialling, interviewed and invited for anti-SARS-CoV-2 antibodies. The seroprevalence was corrected with the aid of the bivariate probit model that jointly estimated individual propensity to agree to participate in the survey and seropositivity. 66,250 individuals were contacted, 6,440 adults agreed to be interviewed and blood samples were obtained from 1,038 participants between May 27 and June 26, 2020. Naïve seroprevalence corrected for test characteristics was 9.0% (7.2–10.8) by CMIA and 10.5% (8.6–12.4) by ELISA. Correction for non-response decreased estimates to 7.4% (5.7–9.2) and 9.1% (7.2–10.9) for CMIA and ELISA, respectively. The most pronounced decrease in bias-corrected seroprevalence was attributed to the history of any illnesses in the past 3 months and COVID-19 testing. Seroconversion was negatively associated with smoking status, self-reported history of allergies and changes in hand-washing habits. These results suggest that even low estimates of seroprevalence can be an overestimation. Serosurvey design should attempt to identify characteristics that are associated both with participation and seropositivity.

Seroprevalence of SARS-Cov-2 Antibodies in Adults, Arkhangelsk, Russia

“…Of those who stated they had not been vaccinated and did not report having previously been ill with COVID-19, 292 (45%) were seropositive, suggesting an appreciable level of unrecognized infection. Our overall estimates of seroprevalence (crude 65%, adjusted 72.6%) is appreciably higher than found in St Petersburg in June 2020 ( 3 ) (10%) or in Chelyabinsk (25%) in September–December 2020 ( 4 ). This result is consistent with the second wave of the pandemic in Russia (peak November–December 2020) being larger than the first (peak May–June 2020); our study started during the vaccination period.…”

“…Few published estimates of antibody seroprevalence for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Russia exist. A St. Petersburg survey in June 2020 used random-digit dialing to contact 66,250 residents; of those, 1,038 provided a blood sample, and the samples had 9%–10% seropositivity ( 3 ). A study conducted in Chelyabinsk (September 28–December 30, 2020) recruited 1,091 high-risk workers (healthcare workers, education staff, and supermarket employees) > 18 years of age.…”

Evaluation of the performance of SARS‐­CoV­‐2 antibody assays for a longitudinal population­based study of COVID‐­19 spread in St. Petersburg, Russia

“…19 We used CMIA Abbott and ELISA Coronapass for the first publication of a populationbased seroprevalence study in May June 2020. 6 The first round of the study analysis showed that the use of ELISA Coronapass results in a slightly higher seroprevalence estimation. This was the initial reason for the independent validation of the test performance.…”

“…Information about the corresponding seroprevalence study in St. Petersburg is available in the detailed report 6 . In brief, we obtained a representative population sample through phone by using random­digit dialing.…”

“…[1][2][3] However, researchers have raised several concerns regarding the nonresponse bias, the nonrepresentative sampling, and the use of nonvalidated tests for SARS-CoV-2 antibodies detection. 4 The first two issues can be addressed by appropriate study design and population sampling strategies 5,6 The latter problem requires the assessment of sensitivity and specificity of antibody assays to guide the correction of serological study results. [7][8][9][10][11] Additional requirements for antibody tests are being lodged for longitudinal serologic studies, but manufacturers rarely report the evaluation of the longterm test performance, for example, decreased longterm sensitivity is an issue that could bias the evaluation of immune response durability.…”