Clinical Trial Info

Safety and Immunogenicity Study of Inactivated Vaccine for Prevention of COVID-19

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The experimental CoronaVac vaccine and placebo were both manufactured by Sinovac Research & Development Co., Ltd.

A total of 552 subjects will be enrolled, with 72 at phase 1, and 480 at phase 2.

Subjects will be assigned to receive two doses of different dosage of experimental vaccine or placebo on the schedule of day 0,28.

Interim Results

Between October 31 and December 2, 2020, 72 participants were enrolled in phase 1, and between December 12 and December 30, 2020, 480 participants were enrolled in phase 2.

500 participants received at least one dose of vaccine or placebo (n=71 for phase 1 and n=479 for phase 2; safety population). In the combined safety profile of phase 1 and phase 2, any adverse reactions within 28 days after injection occurred in 56 (26%) of 219 participants in the 1·5ug group, 63 (29%) of 217 in the 3ug group and 27 (24%) of 114 in the placebo group, without significant difference.

Most adverse reactions were mild and moderate in severity and injection site pain (73[13%]) of 550 participants was the most frequently reported event.

As of March 12, 2021, only one serious adverse event has been reported, which was considered unrelated to vaccination.

In phase 1, seroconversion after the second dose was observed in 27 of 27 participants (100·0% [95%CI 87·3-100·0]) in the 1·5ug groups and 26 of 26 participants (100·0% [86·8-100·0]) in the 3ug group, with the geometric mean titers of 55·0 (95%CI 38·9-77·9) and 117·4 (87·8-157·0). In phase 2, seroconversion was seen in 180 of 186 participants (96·8% [93·1-98·8]) in the 1·5ug group and 180 of 180 participants (100·0% [98·0-100·0]) in the 3ug group, with the geometric mean titers of 86·4 (73·9-101·0) and 142·2 (124·7-162·1).

There were no detectable antibody responses in the placebo groups.