A total of 1000 participants will be equally divided into the two study groups, children of 6-12 years and adolescents of 13-17 years. In each age group, they will have an equal chance to received either one dose of Ad5-nCoV (intramuscular injection) or Ad5-nCoV-IH (nebulized inhalation). The enrollment of the children group will start after the safety profiles in 7 days post-vaccination of the adolescent group have been deemed acceptable. Investigators should try to balance the age and sex of the participants during enrollment.
This is a multicenter, randomized, and open-label study to evaluate the immune responses and safety profiles of children aged 6-12 years and adolescents aged 13-17 years receiving Ad5-nCoV (intramuscular injection) or Ad5-nCoV-IH (nebulized inhalation) ≥ 90 days after receiving two doses of CoronaVac.