Correction: Risk factors for critical COVID-19 illness during Delta- and Omicron-predominant period in Korea; using K-COV-N cohort in the National health insurance service
by Kyung-Shin Lee, Min Jin Go, Youn Young Choi, Min-Kyung Kim, Jaehyun Seong, Ho Kyung Sung, Jaehyun Jeon, Hee-Chang Jang, Myoung-Hee Kim