A decrease in the incidence of encephalitis in South Korea during the COVID‐19 pandemic: A nationwide study between 2010 and 2021

Abstract

Limited data are available on the impact of the coronavirus disease pandemic on encephalitis. Therefore, we evaluated trends in encephalitis in South Korea between 2010 and 2021 using data from the National Health Insurance Service. During the pandemic (February 2020 to 2021), the monthly incidence of encephalitis declined by 0.027 per 100 000 population (95% confidence interval[CI]: −0.055 to 0.001, p = 0.062) compared to that before the pandemic. In subgroup analysis, the estimated coefficient for level change during the pandemic in the 0-4 and 5-9 years age groups were −2.050 (95% CI: −2.972 to −1.128, p < 0.001) and −0.813 (95% CI: −1.399 to −0.227, p = 0.008), respectively. The annual incidence of encephalitis during the pandemic period significantly decreased in the 0-4 and 5-9 years age groups (incidence rate ratio: 0.34 [p = 0.007] and 0.28 [p = 0.024], respectively). The intensive care unit admission rate (39.1% vs. 58.9%, p < 0.001) and cases of death (8.9% vs. 11.1%, p < 0.001) decreased significantly during the pandemic compared to the prepandemic. During the pandemic, the incidence of encephalitis decreased markedly in South Korea, particularly in children aged ≤9 years. In addition, there were changes in the clinical outcome of encephalitis during the COVID-19 pandemic.

Aetiology and Prognosis of Encephalitis in Korean Children: A Retrospective Single-Centre Study, 2005–2020

“…We previously reported that during the early phase of the COVID-19 pandemic in Korea from 2020 to 2021, when stringent non-pharmaceutical interventions (NPIs) were implemented, the incidence of encephalitis was reduced by 66%–72% in children aged 0–9 years. 18 During the same NPIs period, the incidence of community-acquired respiratory viral infections in Korea had also decreased by 8%–25%. 19 This supports the hypothesis that community-acquired infections may be a critical cause or trigger of encephalitis.…”