National trends in asthma prevalence in South Korea before and during the COVID-19 pandemic 1998-2021

<p dir="ltr">To the Editor,</p><p dir="ltr">Since the COVID-19 pandemic has a drastic effect on diverse allergic diseases, research on the critical impact of COVID-19 on asthma has been highlighted internationally. According to previous studies, the prevalence of asthma increased worldwide over the past decades due to pandemic.<a href="https://onlinelibrary.wiley.com/doi/10.1111/cea.14394#cea14394-bib-0001" target="_blank">¹</a>^,<a href="https://onlinelibrary.wiley.com/doi/10.1111/cea.14394#cea14394-bib-0002" target="_blank">²</a> However, previous studies reported in South Korea have conflicting evidence on whether the prevalence of asthma has decreased or increased, especially among adolescents.<a href="https://onlinelibrary.wiley.com/doi/10.1111/cea.14394#cea14394-bib-0003" target="_blank">³</a> Thus, to further understand the context of this extraordinary trend, we examined the trends of age-stratified asthma prevalence in South Koreans before and during the COVID-19 pandemic.<a href="https://onlinelibrary.wiley.com/doi/10.1111/cea.14394#cea14394-bib-0004" target="_blank">⁴</a> The effects of age and other socioeconomic and environmental variables on these trends were analysed using data collected from the Korean National Health and Nutrition Examination Survey (KNHANES), 1998–2021.<a href="https://onlinelibrary.wiley.com/doi/10.1111/cea.14394#cea14394-bib-0005" target="_blank">⁵</a> An annual survey conducted by the Korea Disease Control and Prevention Agency (KDCA), 1998–2021...</p>