Serological survey for SARS-CoV-2 antibodies among tribal communities of Odisha post-second wave.

Background & Objectives: Serial national level serosurveys in India have provided valuable information regarding the spread of COVID-19 pandemic in the general population, but the impact of the ongoing pandemic on the tribal population in India is not well understood. In this study, we evaluated the seroprevalence of COVID-19 antibodies in the tribal population of Odisha post-second wave (September 2021).

Methods: A population-based, age-stratified, cross-sectional study design was adopted for the survey, carried out in seven tribal districts of Odisha from 30 August to 16 September 2021. A multistage random sampling method was used where serum samples were tested for antibodies against the SARS-CoV-2 nucleocapsid (N) protein in each district, and a weighted seroprevalence with 95 per cent confidence interval (CI) was estimated for each district.

Results: A total of 2855 study participants were included from the seven tribal districts of Odisha in the final analysis. The overall weighted seroprevalence was 72.8 per cent (95% CI: 70.1-75.3). Serological prevalence was the highest among 18-44 yr (74.4%, 95% CI: 71.3-77.3) and from Sambalpur district [75.90% (66.90-83.10)]. Among participants, 41.93 per cent had received at least one dose of any COVID-19 vaccine. Kandhamal district had the highest number of fully immunized participants (24.78%), and in Sundergarh district, most of the study participants (58.1%) were unimmunized.

Interpretation & Conclusions: This study found high seroprevalence against SARS-CoV-2 in the tribal population of Odisha. The vaccination coverage is at par with the general population, and efforts to address some knowledge gaps may be needed to improve the coverage in the future.