Heterologous Boost Immunization with Ad5-nCoV After Three-dose Priming with an Inactivated SARS-CoV-2 Vaccine

The orally aerosolized Ad5-nCoV is a replication defective Ad5 vectored COVID-19 vaccine expressing the full-length spike gene of wide-type SARS-CoV-2, Wuhan-Hu-1. The Ad5-nCoV vaccine was supplied in 1.5mL/vial, at a concentration of 1.0 × 1011 viral particles per mL as a liquid formulation. 0.1 ml of Ad5-nCoV vaccine will be aerosolized by using Continuous Vapouring System. Then, the aerosolized droplets will be poured into a disposable suction cup and be inhaled by participants through mouth.

The Ad5-nCoV is a replication defective Ad5 vectored COVID-19 vaccine expressing the full-length spike gene of wide-type SARS-CoV-2, Wuhan-Hu-1. It was supplied in 1·5mL/vial, at a concentration of 1.0 × 1011 viral particles per mL as a liquid formulation. Participants will be administrated 0.5ml（5×1010VP）of Ad5-nCoV vaccine intramuscularly.

CoronaVac is an inactivated whole-virion vaccine with aluminium hydroxide as the adjuvant, prepared with a novel coronavirus (CZ02 strain) inoculated in African green monkey kidney cells (Vero cells). One dose of CoronaVac contains 3 μg of SARS-CoV-2 virion in a 0.5 mL aqueous suspension for injection with 0.45 mg/mL of aluminium.