Safety and immunogenicity of an inactivated virus particle vaccine for SARS-CoV-2, BIV1-CovIran: findings from double-blind, randomised, placebo-controlled, phase I and II clinical trials among healthy adults

Objective Assessing safety and immunogenicity of an inactivated whole virus particle vaccine. Design Single-centre, double-blind, randomised, placebo-controlled, phase I (stage I: 18-50, stage II: 51-75 years), phase II (18-75 years) clinical trials. Setting 29 December 2020 to 22 April 2021. Participants Stage I-phase I: 56 participants; stage II-phase I: 32; phase II: 280. Intervention During stage I, participants randomly (3:3:1) received 3 mu g, 5 mu g vaccine or placebo in a 14-day interval. Participants in stage II received two shots of 5 mu g vaccine or placebo (3:1). In phase II, participants received 5 mu g vaccine or placebo (4:1) in a 28-day interval. Primary and secondary outcome measures Safety assessment and immunogenicity assessment via antibody response and conventional virus neutralisation test (cVNT). Results All adverse events (AEs) were mild or moderate and transient in both phase I and phase II, and no AEs of special interest were reported. The seroconversion-rate of neutralising, antireceptor binding-domain (RBD) and anti-spike-glycoprotein (anti-S) antibodies 14-days after second dose of 5 mu g vaccine in stage I was 70.8% (95% CI 48.9% to 87.4%), 87.5% (95% CI 67.6% to 97.3%), 91.7% (95% CI 73.0% to 99.0%). The antibody titres increased more among 5 mu g than 3 mu g. The corresponding rates for 3 mu g vaccine were 45.8% (95% CI 25.6% to 67.2%), 54.2% (95% CI 32.8% to 74.5%) and 70.8% (95% CI 48.9% to 87.4%), respectively. In stage II, 100% (95% CI 84.6% to 100%), 86.4% (95% CI 65.1% to 97.1%) and 86.4% (95% CI 65.1% to 97.1%) of participants seroconverted for neutralising, anti-RBD and anti-S antibodies. In phase II, the seroconversion rate of neutralising-antibody was 82.8% (95% CI 77.0% to 87.6%), anti-RBD 77.0% (95% CI 70.7% to 82.6%) and anti-S 79.9% (95% CI 73.8% to 85.1%) on day 42. In the cVNT, the sera at 1/64 times dilution would neutralise SARS-CoV-2 among 91.7%, 77.3% and 82.5% of vaccinated participants in phase I-stage I, phase I-stage II and phase II clinical trials, respectively. Conclusions These results support further evaluation of this inactivated whole virus particle vaccine.

Automated summary

This study assessed the safety and immunogenicity of an inactivated whole virus particle vaccine. The results showed that the vaccine had good safety profile in all stages and could effectively induce neutralizing antibodies and antibody responses.