# Sero-Surveillance to Evaluate Trends in the Transmission of SARS-CoV-2 in a Central Indian District

## TL;DR

This study used blood tests to track how many people in Nagpur, India, had been infected with SARS-CoV-2, finding that 80% had antibodies, with higher rates in women and the elderly.

## Contribution

The study provides updated seroprevalence data in a central Indian district, highlighting the impact of vaccination on immunity levels.

## Key findings

- The overall seroprevalence rate in Nagpur was 80%.
- Females had higher seroprevalence rates than males in both municipal and non-municipal areas.
- The vaccinated group had more positive SARS-CoV-2 antibody tests than the unvaccinated group.

## Abstract

Background and objective

The actual community burden of SARS-CoV-2 is undervalued, as the estimates are just the symptomatic infections. The acute phase of the pandemic has waned, and the analytical comparison of infection spread through repeated sero-epidemiological studies is important in the formulation of effective public health strategies. This study investigated the level of seroprevalence of IgG antibodies for the SARS-CoV-2 virus in the Nagpur district, Maharashtra, India.

Materials and methods

The present cross-sectional survey was conducted over three months from September to November 2021 by carrying out a door-to-door survey involving 6129 participants. Among them, 3131 were from municipal areas, while the rest were from non-municipal regions. Data collection was facilitated using Google Forms (Google LLC, Mountain View, California, United States). Venous blood samples were collected, and SARS-CoV-2 antibodies were detected using the COVID KAVACH IgG enzyme-linked immunosorbent assay (ELISA) kit (developed by the National Institute of Virology (NIV), Pune, India). The information collected was then cleaned, coded, and analyzed using Epi Info software (Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA).

Results

The seroprevalence rate was found to be 80% in the whole district. Females had a higher seroprevalence rate in both areas than males. The population aged 60 years and above had the highest seroprevalence rate in both zones. The vaccinated group demonstrated a greater number of individuals testing positive for SARS-CoV-2 compared to the unvaccinated group.

Conclusion

The significant increase in the seroprevalence estimates in relation to the prior survey is because of the significant surge in COVID-19 vaccination coverage after the first wave of the pandemic. The findings of the study imply the dynamic nature of the pandemic and the different degrees of immunity obtained within the community. Ongoing surveillance and research are essential for refining effective strategies to manage and mitigate future pandemics effectively.