Effectiveness of the inactivated COVID-19 vaccine (CoronaVac) in adult population in Indonesia

BackgroundInactivated SARS-CoV-2 vaccine has been included in the national COVID-19 vaccination program in Indonesia since January 2021. The study aims to assess the impacts of inactivated COVID-19 vaccine on infection, hospitalization, and death among adult population aged [≥]18 years in Bali, Indonesia. MethodsTest-negative, case control study was conducted by linking SARS-CoV-2 laboratory records, vaccination, and health administrative data for the period of January 13 to June 30, 2021. Case-subjects were defined as individuals who had a positive RT-PCR test for SARS-CoV-2 during the period; they were matched with controls (tested negative) (1:1) based on age, sex, district of residence, and week of testing. We estimated the odds of vaccination in PCR confirmed, hospitalization and death due to COVID-19, accounting for the presence of comorbidities and prior infection. Vaccine effectiveness was estimated as (1-odds ratio) x 100%. ResultsTotal 109,050 RT-PCR test results were retrieved during the January 13 to June 30, 2021. Of these, 14,168 subjects were eligible for inclusion in the study. Total 5518 matched case-control pairs were analyzed. Adjusted vaccine effectiveness (VE) against laboratory-confirmed SARS-CoV-2 infection was 14.5% (95% confidence interval -11 to 34.2) at 0-13 days after the first dose; 66.7% (95% CI: 58.1-73.5) at [≥]14 days after the second dose. The adjusted effectiveness against hospitalization and COVID-19-associated death was 71.1% (95% CI: 62.9-77.6) and 87.4% (95% CI: 65.1-95.4%) at [≥]14 days after receiving the second dose, respectively. ConclusionsTwo-dose of inactivated CoronaVac vaccine showed high effectiveness against laboratory confirmed COVID-19 infection, hospitalization, and death associated with COVID-19 among adults aged [≥]18 years.