Population-Level Mortality Rates from Novel Coronavirus (COVID-19) in South Korea

Samir Soneji; Hiram Beltrán-Sánchez; JaeWon Yang; Caroline Mann

March 2020. Thus, all data was current as of 22 March 2020. Second, we calculated the number of confirmed cases for each age group by proportionally allocating the total number of confirmed cases according to the case distribution by age group. Third, we calculated the total number of deaths by multiplying the number of confirmed cases and the case fatality rate for each age group. Fourth, we fit a negative binomial regression model on the mortality rates with the number of deaths as the outcome and the population by age as an offset. We then predicted mortality rates from the regression model. The mortality rates equaled the number of deaths divided by the number of person-years lived over the 63-day exposure period (time from first case on 20 January 2020 to 22 March 2020) for each age group. To convert mortality rates to an annual period, we multiplied them by the fraction of the year 2020 represented by the exposure period (i.e., 366 days/63 days). Sixth, we calculated the age-standardized death rates (ASDR) for COVID-19, where the age standard was based on the 2016 population in South Korea. We selected 2016 as the year of standardization because this is the most recent year for which the Vital Statistics Division of Statistics Korea published the ASDR of the leading causes of death (e.g., cancer and heart disease). 10 See Appendix for step-by-step explanation of methods. All rights reserved. No reuse allowed without permission.