An interesting article published in The Lancet Infectious Diseases October 15, 2020 by Xia and others did a randomised double-blind, placebo-controlled phase 1/2 trial in Shangqui City, Liangyuan District Centre for Disease Control and Prevention in Henan Province, China. 

In the phase 1 healthy people aged 18 to 80 who were negative for antibodies against SARS-CoV-2 at the time of screening were separated into two age groups, 18 to 59 years and greater than 60 and they were randomly assigned to receive vaccine or placebo in a two-dose schedule. 

In phase 2 healthy adults aged 18 to 59 were randomly assigned to receive vaccine or placebo in a single dose schedule or on a two-day schedule. 

Participants within each cohort were randomly assigned by stratified block randomisation and allocated to receive vaccine or placebo. 

The primary outcome was to assess safety and immunogenicity of two phases and compare. 

In the phase 1/2 trial the BBIBP/CorV inactivated vaccine given as a two dose immunisation was found to be safe and well-tolerated at all three doses in both age groups. 

A robust human immune response was observed in 100% of vaccine recipients. 

In preclinical studies, the authors had shown that immunisation with the vaccine induced high levels of neutralising antibody titres in mice, rats, guinea pigs, rabbits and non-human primates. 

The most common adverse reactions were pain and fever, which were reported in a small proportion of vaccine recipients with no significant difference across the groups. All adverse events were mild or moderate in severity. 

There were a higher number of systemic adverse events in the placebo group but during the follow-up, monitoring of respiratory symptoms, no upper respiratory tract infections were detected. 

It is concluded that the inactivated SARS-CoV-2 vaccine, BBIBP/CorV was tolerable and immunogenic in healthy people. They found a rapid humoral response against SARS-CoV-2 from day four after the first inoculation and 100% seroconversion was in all participants on day 42. 

The days 0 and 21 days 0 and 28 two day immunisation schedules elicited significantly greater neutralising antibodies status than days 0 and 14 schedule and the single immunisation schedule. 

Dr Paul Ettlinger 
The London General Practice 

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