The trial will be carried out across Melbourne and Brisbane, and is the first human trial of a vaccine specifically for COVID-19 to take place in Australia.
This vaccine is actually based on a vaccine that was already in development for influenza. But how might it work against SARS-CoV-2, the coronavirus that causes COVID-19?
What’s in the mix?
Vaccines trigger an immune response by introducing the cells of our immune system to a virus in a safe way, without any exposure to the pathogen itself.
All vaccines have to do two things. The first is make our immune cells bind to and “eat up” the vaccine. The second is to activate these immune cells so they’re prepared to fight the current and any subsequent threats from the virus in question.
We often add molecules called adjuvants to vaccines to deliver a danger signal to the immune system, activate immune cells and trigger a strong immune response.
The Novavax vaccine is what we call a “subunit” vaccine because, instead of delivering the whole virus, it delivers only part of it. The element of SARS-CoV-2 in this vaccine is the spike protein, which is found on the surface of the virus.
By targeting a particular protein, a subunit vaccine is a great way to focus the immune response.
However, protein by itself is not very good at binding to and activating the cells of our immune system. Proteins are generally soluble, which doesn’t appeal to immune cells. They like something they can chew on.
So instead of soluble protein, Novavax has assembled the SARS-CoV-2 spike protein into very small particles, called nanoparticles. To immune cells, these nanoparticles look like little viruses, so immune cells can bind to these pre-packaged chunks of protein, rapidly engulfing them and becoming activated.
The Novavax vaccine also contains an adjuvant called Matrix-M. While the nanoparticles deliver a modest danger signal, Matrix-M can be added to deliver a much stronger danger signal and really wake up the immune system.