Risk Factors of Symptoms Occurrence in SARS-CoV-2 Infection After Implementing Vaccination Program in Bali

The real-world data have shown the effectiveness of many variants of Covid-19 vaccines. However, many people still get infected and indicate various symptoms after vaccination. This study aims to assess the risk factors of symptom occurrence in Covid-19 after implementing the vaccination program in Bali. This retrospective, case-control study used surveillance data include demographic, vaccination status, symptom occurrence, and severity from Pemecutan Kaja Village, North Denpasar district. Participants were included if they tested positive for SARS-CoV-2 with a minimum age of 18 years old. There was a total of 592 data on Covid-19 patients, the cases group was symptomatic and the control group was asymptomatic. Between May to September 2021, the vaccination program was implemented in Bali with Sinovac and Astra Zeneca. The risk factor analysis showed that age (OR 2.57, 95% CI 1.376-4.818; p = 0,003) and vaccination status (OR 3.104, 95% CI 2.089-4.611; p = < 0,001) were associated with symptom occurrence in Covid-19. Elderly and unvaccinated subjects have a higher risk of developing symptomatic SARS-CoV-2 infection. Vaccinations were not 100% effective in protecting people from infection, but almost all symptoms were reported as less frequent in vaccinated. A better understanding of the risk factor of severe infection has apparent implications for additional prevention and treatment for those with a higher risk of developing the severe condition. Adopting strategies are required to facing the probability of infection and controlling any future epidemic.