Risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections: a nationwide population-based study

BACKGROUND: The coronavirus disease 2019 (COVID-19) has rapidly turned into a public health emergency worldwide; however, the risk factors for infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have not been well-described. We aimed to identify the clinical risk factors for SARS-CoV-2 infections in Korea, where social distancing and face masks have been strongly recommended. METHODS: The data of individuals who underwent the reverse transcription polymerase chain reaction test for SARS-CoV-2 between January 3 and May 31, 2020 were retrieved from the Health Insurance Review and Assessment Service dataset. We used multivariable logistic regression models to identify the risk factors for SARS-CoV-2 infections in the population. RESULTS: We retrieved the results of 219,729 SARS-CoV-2 tests, of which 7,333 were positive results. In the multivariable analysis, female sex was associated with a higher risk of testing positive for SARS-CoV-2 [odds ratio (OR) =1.30, 95% confidence interval (CI): 1.24–1.37, P<0.0001]. Additionally, populations living in areas that had large outbreaks of COVID-19 were at an increased risk of testing positive for SARS-CoV-2 (OR =6.87, 95% CI: 6.55–7.21, P<0.0001). The odds of a positive test were greater for the Medical Aid beneficiaries (OR =1.99, 95% CI: 1.82–2.18, P<0.0001) than for the National Health Insurance beneficiaries. Individuals with diabetes mellitus (DM) were more likely to test positive (OR =1.15, 95% CI: 1.07–1.24, P=0.0002). CONCLUSIONS: Women, individuals living in areas with large outbreaks of COVID-19, Medical Aid beneficiaries, and individuals with DM might have greater risks of contracting SARS-CoV-2 infections despite practicing social distancing and using face masks.