Study on Sequential Immunization of Inactivated SARS-CoV-2 Vaccine and Recombinant SARS-CoV-2 Vaccine (Ad5 Vector)

Summary

This is a randomized, observer-blind, parallel-controlled study, for evaluation of safety and immunogenicity of sequential immunization of a recombinant SARS-CoV-2 vaccine (adenovirus type 5 vector) in Chinese healthy adults aged 18-59 years after the priming vaccination of inactivated vaccine. 300 healthy subjects aged 18-59 years will be recruited in this study. Of them, 200 subjects who have been vaccinated with two dose of inactive SARS-CoV-2 vaccine will be recruited and randomized at a 1:1 ratio to receive a booster dose of inactivated SARS-CoV-2 vaccine or recombinant SARS-CoV-2 Ad5 vectored vaccine at 3\~6 months later. Other 100 subjects who have been vaccinated with one dose of inactivated SARS-CoV-2 vaccine will be recruited and randomized at a 1:1 ratio to receive a booster dose of inactivated SARS-CoV-2 vaccine or recombinant SARS-CoV-2 Ad5 vectored vaccine at 1\~3 months later. The occurrence of adverse events within 28 days and serious adverse events within 6 months after vaccination will be observed. In addition, blood samples will be collected on day 0 before the boosting with ad5 vectored vaccine and on day 14, 28 and month 6 after the boosting. Serum antibody levels, cellular immune responses and the subgroups or germlines of the specific B cells will be analyzed. Each subject will remain in this study for approximately 6 months.

Timeline

Start

2021-05-25

Primary completion

2021-07-25

Completion

2021-12-25

Publications

• Han X, Jiang H, Zheng H, Jin P, Xu L, Wang F, Li S, Shao C, Jia S, Feng J, Xu M, Li J. Systemic immune profiling of heterologous versus homologous boosting of COVID-19 vaccination. J Transl Med. 2026 Jul 16. doi: 10.1186/s12967-026-08620-1. Online ahead of print.
• Li J, Hou L, Guo X, Jin P, Wu S, Zhu J, Pan H, Wang X, Song Z, Wan J, Cui L, Li J, Chen Y, Wang X, Jin L, Liu J, Shi F, Xu X, Zhu T, Chen W, Zhu F. Heterologous AD5-nCOV plus CoronaVac versus homologous CoronaVac vaccination: a randomized phase 4 trial. Nat Med. 2022 Feb;28(2):401-409. doi: 10.1038/s41591-021-01677-z. Epub 2022 Jan 27.

Drugs

Indications