The vaccine is now mostly referred to as the New Crown vaccine, with a maximum of 8 weeks between the first and second shots. Currently, single, double and triple doses of the new crown vaccine are common. 1. Single shot: mainly refers to the adenovirus vector vaccine, which usually requires only one vaccination, so there is no interval between the second shot. 2. Double-dose: mainly refers to the new inactivated coronavirus vaccine, which requires two doses for primary immunization, and the interval between the first and second doses is 3 weeks or more, with a maximum interval of 8 weeks. 3. Three doses: mainly refers to the recombinant subunit vaccine, this type of vaccine requires a full course of three doses, and the interval between the two adjacent doses is recommended to be ≥4 weeks. The second dose should be completed within 8 weeks after the first dose. Vaccine recipients need to strictly follow the requirements of professionals to receive the second or third dose of vaccine within the specified timeframe so that the vaccine can achieve the best immunization effect.