This study examines the impact of social distancing and school closures on the dynamics of the COVID-19 outbreak in Wuhan and Shanghai, China. Intense nonpharmaceutical interventions were implemented to control the spread of the virus. Contact survey data from Wuhan and Shanghai, as well as contact-tracing information from Hunan province, were analyzed to understand changes in contact patterns and age-specific susceptibility to infection. The results show that daily contacts were reduced by seven to eight times during the social distancing period, with most interactions restricted to households. Children aged 0 to 14 years were found to be less susceptible to SARS-CoV-2 infection compared to adults aged 15 to 64 years, while individuals over 65 years of age were more susceptible. A transmission model was developed to study the impact of social distancing and school closures. The model indicates that social distancing alone is sufficient to control COVID-19, while school closures can reduce peak incidence by 40 to 60% and delay the epidemic. The study highlights the importance of age-specific interventions and the need for targeted strategies to long-term control of the virus.This study examines the impact of social distancing and school closures on the dynamics of the COVID-19 outbreak in Wuhan and Shanghai, China. Intense nonpharmaceutical interventions were implemented to control the spread of the virus. Contact survey data from Wuhan and Shanghai, as well as contact-tracing information from Hunan province, were analyzed to understand changes in contact patterns and age-specific susceptibility to infection. The results show that daily contacts were reduced by seven to eight times during the social distancing period, with most interactions restricted to households. Children aged 0 to 14 years were found to be less susceptible to SARS-CoV-2 infection compared to adults aged 15 to 64 years, while individuals over 65 years of age were more susceptible. A transmission model was developed to study the impact of social distancing and school closures. The model indicates that social distancing alone is sufficient to control COVID-19, while school closures can reduce peak incidence by 40 to 60% and delay the epidemic. The study highlights the importance of age-specific interventions and the need for targeted strategies to long-term control of the virus.