SARS CoV-2 Antibody Seroprevalence in Jakarta, Indonesia: March 2021 (preprint)

ABSTRACT

Background: The dynamics of SARS CoV-2 transmission among urban centers in low- and middle-income countries (LMICs) remains poorly understood. We aimed to estimate the seroprevalence of SARS CoV-2 antibodies in Jakarta, Indonesia – the country in Southeast Asia with the highest number of reported cases and deaths, to increase knowledge of SARS CoV-2 transmission in large urban settings in Southeast Asia. Methods: We conducted a population-based serosurvey among individuals aged one year or older across Jakarta’s six districts. A stratified multi-stage sampling design was employed. Samples were stratified by district, slum and non-slum residency, sex, and age-group. Participants were interviewed to collect information on socio-demographic characteristics, weight and height measurements, and a history of COVID-19 diagnosis and/or recent contact. Blood samples were collected and tested for IgG against three different SARS-CoV-2 antigens using the Human IgG Tetracore® FlexImmArray™ SARS-CoV-2 Human IgG test. Seroprevalence was estimated after applying sample weights and adjusting for cluster characteristics. Findings: During March 2021, 4,919 individuals were enrolled in the study. The weighted estimate of seroprevalence was 44·5% (95% CI 42·5-46·5). Seroprevalence was highest among adults 30-49 years old, with higher seroprevalence detected in women and among those with a body mass index that was overweight or obese. Respondents residing in slum areas were 1·3-fold more likely to be seropositive than non-slum residents. We estimated that 4,717,000 of Jakarta’s 10·6 million residents had prior SARS CoV-2 infection. These findings suggest that for every reported confirmed case, approximately 10 infections were undiagnosed or underreported. Interpretation: Approximately one year after the first cases of COVID-19 were confirmed, close to half of Jakarta’s residents have been infected by SARS CoV-2. Urban centers in LMICs remain the places in the world most vulnerable to SARS CoV-2 transmission, as well as its adverse health and social consequences.