Comparison of the second and third waves of the COVID-19 pandemic in South Korea: Importance of early public health intervention

Seong, Hye; Hyun, Hak Jun; Yun, Jin Gu; Noh, Ji Yun; Cheong, Hee Jin; Kim, Woo Joo; Song, Joon Young

Objectives We aimed to compare epidemiologic features of second and third COVID-19 pandemic waves in South Korea. Methods Nationwide COVID-19 data was collected during the study period (May 6–December 30). The degree of social activities was also estimated using the internet searching trend analysis program for leisure-related keywords including “eating-out,” “trip,” and “get directions” (transportation). We compared the demographics, transmission chains, case fatality rates, social activity level, and public health responses between second (August 13–September 18) and third (November 4–present) waves. Results Compared to the second wave, the third wave was characterized by delayed social distancing reinforcement (3 vs. 15 days), longer duration (36 vs. > 56 days) and higher fatality rates (0.91% vs. 1.26%). There was a significant difference in transmission chains of the second and third waves of the COVID-19 pandemic (p < 0.01). During the third wave compared with the second wave, the proportion of local clusters (24.8% vs. 45.7%) was lower, while those of personal contact transmission (38.5% vs. 25.9%) and unknown routes of transmission (23.5% vs. 20.8%) were higher. Conclusion Early and timely interventions with strengthened social distancing policies should be implemented to effectively suppress and control the COVID-19 pandemic.