Volunteers safely administered first dose in clinical trial of Melbourne-made COVID-19 vaccines
The first six participants in the clinical trial of two Melbourne-made COVID-19 vaccines have been safely administered their doses, a significant moment in the development of the new vaccine candidates.
The two vaccine candidates were created by researchers at the Peter Doherty Institute for Infection and Immunity (Doherty Institute) and Monash Institute of Pharmaceutical Sciences (MIPS) and are distinct from existing vaccines in use around the globe.
These vaccines focus the immune response on the tip of the SARS-CoV-2 spike protein, called the receptor binding domain (RBD). The RBD enables the virus to enter and infect cells in the body and elicits over 90 per cent of neutralising antibodies (antibodies that can block the virus) following SARS-CoV-2 infection.
The two candidates are:
- Doherty RBD protein vaccine – uses part of the virus protein, rather than genetic material or another virus, to elicit an immune response.
- MIPS RBD mRNA vaccine – represents the virus genetic sequence that codes for the tip of the spike, which will lead to production of the RBD protein.
In addition, they are ‘proof-of-principle’ variant vaccines that present the Beta variant to the immune system, which was of the greatest concern when these vaccines were designed. Furthermore, the Beta variant has two of the same key RBD mutations as the Omicron variants (BA.1 and BA.2), so they may also improve immunity to Omicron.
The randomised, double-blind, placebo-controlled study is the first time a side-by-side comparison will be undertaken of protein and mRNA based COVID-19 vaccine platforms, each vaccine at three dose levels (lower, intermediate and higher doses).
It will assess the safety and efficacy of a single dose of these vaccines as a fourth dose of a COVID-19 vaccine, with all participants already having received their third dose of an existing vaccine at least three months prior.
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