RESUMO
BACKGROUND: Understanding the actual prevalence of COVID-19 transmission in the community is vital for strategic responses to the pandemic. This study aims to estimate the actual infection of COVID-19 through a seroprevalence survey and to predict infection fatality rate (IFR) in Tanjung Priok, the hardest-hit sub-district by the COVID-19 in Jakarta, Indonesia. METHODS: We conducted a venous blood sampling (phlebotomy) to 3,196 individuals in Tanjung Priok between Nov 23, 2020, and Feb 19, 2021 to detect their antibodies against SARS-CoV-2. Using an enumerator-administered questionnaire, we collected data on the respondents' demographic characteristics, COVID-19 test history, COVID-19 symptoms in the last 14 days, comorbidities, and protective behaviours during the last month. We employed descriptive analysis to estimate the seroprevalence and IFR. FINDINGS: The prevalence of Antibody against SARS-CoV-2 was 28.52% (95% CI 25.44-31.81%), with the result being higher in females than males (OR 1.20; 95% CI 1.02-1.42). By the end of the data collection (February 9, 2021), the cumulative cases of COVID-19 in Tanjung Priok were reported to be experienced by 9,861 people (2.4%). Those aged 45-65 were more likely to be seropositive than 15-19 years old (OR 1.42; 95% CI 1.05-1.92). Nearly one third (31%) of the subjects who developed at least one COVID-19 symptom in the last 14 days of the data collection were seropositive. The estimated IFR was 0.08% (95% CI 0.07-0.09), with a higher figure recorded in males (0.09; 95% CI 0.08-0.10) than females (0.07; 95% CI 0.06-0.08), and oldest age group (45-65) (0.21; 95% CI 0.18-0.23) than other younger groups. CONCLUSION: An under-reporting issue was found between the estimated COVID-19 seroprevalence and the reported cumulative cases in Tanjung Priok. More efforts are required to amplify epidemiological surveillance by the provincial and local governments.