BackgroundThe COVID-19 epidemic and the related containment strategies may affect parental and pediatric health behaviors. ObjectiveThe goal of this study was to assess the change in children’s and adolescents’ prevention and vaccination behaviors amid China’s COVID-19 epidemic. MethodsWe conducted a cross-sectional online survey in mid-March 2020 using proportional quota sampling in Wuhan (the epidemic epicenter) and Shanghai (a nonepicenter). Data were collected from 1655 parents with children aged 3 to 17 years. Children’s and adolescents’ prevention behaviors and regular vaccination behaviors before and during the epidemic were assessed. Descriptive analyses were used to investigate respondents’ characteristics, public health prevention behaviors, unproven protection behaviors, and vaccination behaviors before and during the COVID-19 epidemic. Univariate analyses were performed to compare differences in outcome measures between cities and family characteristics, using chi-square tests or Fisher exact tests (if expected frequency was