Change in Severity and Clinical Manifestation of MIS-C Over SARS-CoV-2 Variant Outbreaks in Korea

• Published in: Journal of Korean medical science Vol. 38; no. 30; p. e225
• Main Authors: Choe, Young June, Choi, Eun Hwa, Choi, Jong Woon, Eun, Byung Wook, Eun, Lucy Youngmin, Kim, Yae-Jean, Kim, Yeo Hyang, Kim, Young A, Kim, Yun-Kyung, Kwak, Ji Hee, Lee, Hyukmin, Park, June Dong, Jung, Yeon Haw, Gwack, Jin, Lee, Sangwon
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Academy of Medical Sciences 31.07.2023
• Subjects: Child; COVID-19 - epidemiology; Disease Outbreaks; Humans; Original; Republic of Korea - epidemiology; SARS-CoV-2; Republic of Korea; COVID-19; MIS-C; SARS-CoV-2
• ISSN: 1011-8934; 1598-6357
• DOI: 10.3346/jkms.2023.38.e225

There is difference in the incidence of multi-system inflammatory syndrome in children (MIS-C) in patients with different variants of severe acute respiratory syndrome coronavirus 2, however, little is known about the epidemiology in Asian countries. We investigated and compared the epidemiology of the MIS-C during omicron-dominant period with that of previous periods in South Korea. We obtained clinical, epidemiological and laboratory data on MIS-C cases from national MIS-C surveillance in South Korea. We defined pre-delta period as January 2020-May 2021; delta period as June 2021-December 2021; and omicron period as January 2022-April 2022. We describe the clinical characteristics and outcomes of MIS-C patients by period. A total of 91 cases were assessed to be MIS-C cases. Number of MIS-C cases have increased from six cases during pre-delta period to 66 cases during omicron period, while the incidence rate (the number of MIS-C cases per 100,000 cases of reported coronavirus disease 2019) has decreased from 38.5 cases per 100,000 (95% confidence interval [CI], 14.1-83.9) during pre-delta period to 1.6 cases per 100,000 (95% CI, 1.2-2.0) during omicron periods. During pre-delta period, 66.7% and 100% had hypotension and gastrointestinal involvement, respectively; while during omicron period, 12.1% and 6.1% had such clinical manifestations. Fifty percent of pre-delta MIS-C patients were taken intensive care unit (ICU) cares, while 10.6% of patients during omicron periods were in ICUs. Omicron period were associated with less severe clinical manifestation compared to pre-delta and delta periods. Although incidence rate of MIS-C was lower for the omicron period than pre-delta and delta periods, number of patients reported with MIS-C may pose a substantial clinical burden.