Abstract
<jats:sec> <jats:title>Introduction:</jats:title> <jats:p>In an interim analysis of a Phase III trial in the United States in late 2020, the AZD1222 COVID-19 vaccine showed 79% efficacy in preventing COVID-19 symptoms. The study aims to determine the effectiveness of the AZD1222 vaccine against COVID-19.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods:</jats:title> <jats:p>We conducted a case-control study among adults aged 18 years and older from August 14, 2021, to October 21, 2021, following the implementation of a two-dose AZD1222 vaccination program. Cases were defined as individuals with clinically diagnosed COVID-19 confirmed by RTPCR, whereas controls were individuals without a COVID-19 diagnosis. Data collection was carried out from August 14 to October 11, 2021. Clinical data for cases were obtained from hospital medical records, while data for controls were collected through self-administered questionnaires using the LimeSurvey platform. Vaccine effectiveness was assessed using logistic regression, adjusting for age, sex, and comorbidities.</jats:p> </jats:sec> <jats:sec> <jats:title>Results:</jats:title> <jats:p>2,915 individuals met the study sample criteria, comprising 1,366 subjects and 1,549 controls. Adjusted vaccination effectiveness in preventing symptomatic COVID-19 was 91.87% (95% CI, 89.23-93.87, P < 0.001) in the 14 days following the second dose. After the second dose, the adjusted vaccination effectiveness in preventing moderate, severe, or critical COVID-19 was 97.81% (95% CI, 95.71-98.88, P < 0.001).</jats:p> </jats:sec> <jats:sec> <jats:title>Discussion:</jats:title> <jats:p>The results of this study show that the AZD1222 vaccine supports the effectiveness of AZD1222 vaccines in preventing symptomatic and severe COVID-19 outcomes. The results of this study are in line with the results of previous clinical trials that show that full vaccination provides protection for the community. Differences in estimated effectiveness values from different studies can be due to differences in population characteristics, variant types, and how vaccines are launched.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusion:</jats:title> <jats:p>The vaccine AZD1222 is effective in preventing symptomatic and moderate to severe COVID-19 in adults in Indonesia, especially after two doses. The results of this study show that AZD1222 can be used in national immunization strategies to reduce the number of serious diseases and health problems.</jats:p> </jats:sec>