Changes in mortality rate of the general population during the COVID-19 pandemic: an interrupted time series study in Korea.

BACKGROUND: Unlike other countries, South Korea did not implement a large-scale lockdown or closure of businesses to manage the coronavirus disease 2019 (COVID-19) pandemic, but relied on changes in population behaviours and early isolation and treatment of patients. It is important to evaluate the effectiveness of such alternative strategies on the mortality of the general population. METHODS: Mortality and monthly population data from 2013 to 2020 were obtained. A quasi-Poisson regression model adjusting for age structure, seasonality and time was used to evaluate whether underlying trends for monthly mortality rate have changed with the pandemic. Stratification analyses based on sex and location of deaths (inside vs outside of medical facilities) were conducted. RESULTS: The risk estimates showed no changes in non-accidental mortality during the COVID-19 pandemic [relative risk (RR) (95% confidence interval, 95% CI), slope change: 1.00 (1.00, 1.01), step change: 0.99 (0.97, 1.01)] compared with those before the pandemic. In cause-specific analysis, there was an abrupt and sustained decrease in the mortality rate of respiratory diseases [RR (95% CI), step change: 0.81 (0.77, 0.84)]. In the analysis of deaths by location, an increase in non-accidental mortality [RR (95% CI), slope change: 1.01 (1.01, 1.02), step change: 1.16 (1.11, 1.22)] and several cause-specific mortalities was observed outside of medical facilities. CONCLUSIONS: The non-accidental mortality rate in South Korea for the first year of the pandemic followed the historical trends. However, there was a decrease in mortality associated with respiratory diseases, and an increase in mortality occurring outside of medical facilities. The findings may be attributed to changes in public behaviours, and availability of medical resources during the pandemic.

Decrease in Ambient Fine Particulate Matter during COVID-19 Crisis and Corresponding Health Benefits in Seoul, Korea.

Both domestic emissions and transported pollutants from neighboring countries affect the ambient fine particulate matter (PM2.5) concentration of Seoul, Korea. Diverse measures to control the coronavirus disease 2019 (COVID-19), such as social distancing and increased telecommuting in Korea and the stringent lockdown measures of China, may reduce domestic emissions and levels of transported pollutants, respectively. In addition, wearing a particulate-filtering respirator may have decreased the absolute PM2.5 exposure level for individuals. Therefore, this study estimated the acute health benefits of PM2.5 reduction and changes in public behavior during the COVID-19 crisis in Seoul, Korea. To calculate the mortality burden attributable to PM2.5, we obtained residents' registration data, mortality data, and air pollution monitoring data for Seoul from publicly available databases. Relative risks were derived from previous time-series studies. We used the attributable fraction to estimate the number of excessive deaths attributable to acute PM2.5 exposure during January to April, yearly, from 2016 to 2020, and the number of mortalities avoided from PM2.5 reduction and respirator use observed in 2020. The average PM2.5 concentration from January to April in 2020 (25.6 µg/m3) was the lowest in the last 5 years. At least -4.1 µg/m3 (95% CI: -7.2, -0.9) change in ambient PM2.5 in Seoul was observed in 2020 compared to the previous 4 years. Overall, 37.6 (95% CI: 32.6, 42.5) non-accidental; 7.0 (95% CI: 5.7, 8.4) cardiovascular; and 4.7 (95% CI: 3.4, 6.1) respiratory mortalities were avoided due to PM2.5 reduction in 2020. By considering the effects of particulate respirator, decreases of 102.5 (95% CI: 89.0, 115.9) non-accidental; 19.1 (95% CI: 15.6, 22.9) cardiovascular; and 12.9 (95% CI: 9.2, 16.5) respiratory mortalities were estimated. We estimated that 37 lives were saved due to the PM2.5 reduction related to COVID-19 in Seoul, Korea. The health benefit may be greater due to the popular use of particulate-filtering respirators during the COVID-19 crisis. Future studies with daily mortality data are needed to verify our study estimates.