National trends in the prevalence of hepatitis B and C in South Korea, before and during the COVID-19 pandemic (2007-2021) - a nationwide representative study

OBJECTIVE: Due to the various changes caused by the COVID-19 pandemic, some infectious diseases showed different epidemiology and prevalence during the pandemic. However, there is a lack of comprehensive studies on trends in the prevalence of hepatitis B and C related to the pandemic. Thus, we compared the prevalence of hepatitis B and C before and during the COVID-19 pandemic in South Korea. SUBJECTS AND METHODS: We conducted a comprehensive trend analysis with a nationwide serial cross-sectional survey from 2007 to 2021 (n=86,931) using the Korea National Health and Nutrition Examination Survey (KNHANES). The changes in the prevalence of hepatitis B and C were evaluated using a weighted regression mod-el to assess the impact of the COVID-19 pandemic. RESULTS: From 2007 to 2021, 86,931 Korean adults aged 19 or older were included in the KN-HANES data. The prevalence of hepatitis B showed a declining trend until the onset of the pandem-ic (1.80% in 2007-2009; 1.08% in 2016-2019; and 1.01% in 2020), at which point this trend reversed (1.39% in 2021). The prevalence of hepatitis C re-mained stable (0.14% in 2007-2009 and 0.18% in 2016-2019), with no particular surge related to the COVID-19 pandemic (beta diff,-0.002; 95% CI,-0.761 to 0.756). For hepatitis B, old age was identified as a pandemic-related vulnerable factor (ratio of odds ratio, 1.68; 95% CI, 1.05-2.70). CONCLUSIONS: In this study, unlike other infectious diseases, hepatitis B and C did not show a decreasing trend during the pandemic. In particular, hepatitis B showed a rebound trend during the pandemic, which was noticeable in those aged 60 or older. Further studies are need-ed to support these findings.