Estimated prevalence and trends in smoking among adolescents in South Korea,2005-2021:a nationwide serial study

Background Although smoking is classified as a risk factor for severe COVID-19 outcomes,there is a scarcity of studies on prevalence of smoking during the COVID-19 pandemic.Thus,this study aims to analyze the trends of prevalence of smoking in adolescents over the COVID-19 pandemic period.Methods The present study used data from middle to high school adolescents between 2005 and 2021 who participated in the Korea Youth Risk Behavior Web-based Survey(KYRBS).We evaluated the smoking prevalence(ever or daily)by year groups and estimated the slope in smoking prevalence before and during the pandemic.Results A total of 1,137,823 adolescents participated in the study[mean age,15.04 years[95%confidence interval(CI)15.03-15.06];and male,52.4%(95%CI 51.7-53.1)].The prevalence of ever smokers was 27.7%(95%CI 27.3-28.1)between 2005 and 2008 but decreased to 9.8%(95%CI 9.3-10.3)in 2021.A consistent trend was found in daily smokers,as the estimates decreased from 5.4%(95%CI 5.2-5.6)between 2005 and 2008 to 2.3%(95%CI 2.1-2.5)in 2021.However,the downward slope in the overall prevalence of ever smokers and daily smokers became less pronounced in the COVID-19 pandemic period than in the pre-pandemic period.In the subgroup with substance use,the decreasing slope in daily smokers was significantly more pronounced during the pandemic than during the pre-pandemic period.Conclusions The proportion of ever smokers and daily smokers showed a less pronounced decreasing trend during the pandemic.The findings of our study provide an overall understanding of the pandemic's impact on smoking prevalence in adolescents.