A sero-epidemiological study after two waves of the COVID-19 epidemic.

Background: The COVID-19 situation in Maldives have evolved since the epidemic began in March 2020 with unprecedented increase in cases since mid-July 2019 with over 8000 cases at the end of August 2020.

Objective: The aim of the sero-epidemiological investigation is to obtain a sense of the population exposure to the SARS-CoV-2 by measuring the seroprevalence of antibodies to COVID-19 in the general population.

Methods: A population-based, age-stratified prospective method was employed to find out the key epidemiological and serologic characteristics of COVID-19 virus in this study.

Results: The results showed that seroprevalence in the population was 13%. The factors that were associated with antibody results included age (OR: 4.0, CI: 1.7-9.0), nationality (OR: 12.9, CI: 8.3-19.7), being diagnosed for COVID-19 (OR: 24.7, CI: 15.9-38.4) and having symptoms of COVID-19 (OR: 2.0, CI: 1.5-2.8). There was a gradual decrease in the antibody levels from 19 days to 250 days. The mean duration of the presence of antibodies in this study was found to be 124 days.

Conclusions: While the seroprevalence provides a measure that can be used to predict community transmission risk of the disease, the extent of functional immunity provided by antibody titres is still not clear. It is acknowledged that other mechanisms of protection such as T cell mediated immunity will play an important role in providing individual protection.