Peer review confirms Novavax effective against emerging variant

Anastasia Tsirtsakis

6/05/2021 2:52:25 PM

While the vaccine’s efficacy rate is significantly lower against the South African variant than the original strain, there are other factors to consider in a real-world context.

Novavax vaccine.
Associate Professor Paul Griffin says Novavax is sure to be an important part of Australia's vaccine strategy.

The research, published in The New England Journal of Medicine, has confirmed interim findings released earlier this year: Novavax’s COVID vaccine is effective against the South African COVID variant, B.1.351.
As part of the phase 2a–b trial in South Africa, 2684 participants received two doses of the protein subunit vaccine, and predominantly mild-to-moderate COVID-19 developed in 15 vaccinated people compared to 29 in the placebo group, showing an efficacy rate of 49.4%.
Efficacy jumped to 60.1% when looking at the results for HIV-negative participants, who accounted for 94% of the study sample.
Of 41 sequenced isolates, 38 were the B.1.351 variant, and post-hoc vaccine efficacy was 51%.
Researchers believe the HIV-positive volunteers, who accounted for 6%, may have had a lower immune response due to the impact of their ongoing treatment.
Compared to the vaccine’s efficacy rate of 89.3% for the original strain, the results for the variant are rather low.
But infectious diseases physician and microbiologist, Associate Professor Paul Griffin, who was a Principal Investigator for Novavax’s phase 1 study, said the trial results are not necessarily reflective of the big picture.
‘While it is important to do these studies, they are relatively small studies compared to the volume of information we have overall in terms of how well the vaccines work, and so often there are other factors that impact on what the perceived efficacy is from these smaller studies looking specifically at these variants,’ he told newsGP.
‘So while 50% might sound suboptimal compared to the overall efficacy of this and other vaccines, it’s likely to actually not be as significantly affected as these results might suggest.’
In comparison to Novavax, Pfizer claims its vaccine is 100% effective in preventing COVID-19 in South Africa, where B.1.351 is prevalent, while AstraZeneca has an efficacy of 10.4% against mild-to -moderate B.1.351 infections.
While phase 3 trials are still underway in the US and Mexico, early clinical testing has shown Novavax is safe and well-tolerated, causing mainly mild local side effects, such as pain and tenderness, while larger trials have shown adverse events occurred at low levels similar with placebo groups.
‘The thing to point out with Novavax is … it’s a much more tried and tested platform and traditional platform as opposed to some other vaccines we’re seeing, and doesn’t so far have any very significant side effects like we’ve seen with the thrombosis and thrombocytopenia complications of potentially the viral vectored vaccines,’ Associate Professor Griffin said.
‘So … it does look to be a vaccine that’ll be a really important part of our strategy moving forward.’
While vaccines are helping developed countries gain control of the virus, the pandemic continues to rage in poorer nations such as India and Brazil. Concerns are mounting over the emergence of variants, continuing to raise questions about how effective the vaccines will be once global border controls start to ease. 
The spotlight has been on mRNA vaccines, such as those by Pfizer and Moderna, which can be rapidly adapted to address mutations.
But according to Associate Professor Griffin, all of the COVID vaccines on the market have that potential.
‘Realistically, we can add or substitute in a vaccine for a new strain probably within a matter of a small number of months,’ he said.
‘There’s also a well-established pathway now in terms of what sort of testing would be needed to essentially roll those out in terms of demonstrating neutralising antibodies, so laboratory studies that are pretty easy to do.
‘So if there was truly a new escape variant or mutant that required a new vaccine, most of the front runners could do that in a relatively short space of time.’
Gregory Glenn, President of Research and Development at Novavax, believes the data reinforces the ‘encouraging safety profile and cross-protective effect across variants’ seen in studies of the vaccine to date.
‘It also demonstrates that ongoing evaluation of COVID-19 vaccine efficacy against SARS-CoV-2 variants is urgently needed to inform vaccine development and use,’ he said.
Early projections had indicated Novavax would be available in Australia by mid-2021, but unforeseen challenges in recruiting trial volunteers has set that timeline back. But Associate Professor Griffin says they are now ‘back on track’.
‘Those studies are progressing well and while our initial timeframe has obviously not been met … it’s hard to know exactly when it will be available, because it really just depends on having the data to support its use,’ he said.
‘I think it’s certainly looking likely that that will be sometime this year.’
Pending the successful completion of phase 3 trials and approval from the Therapeutic Goods Administration, Australia has signed up for 41 million doses of Novavax – with the capacity to secure an additional 10 million.
But as with Pfizer, Australia will be reliant on offshore supply, with doses set to be manufactured in several locations across Europe. While CSL has said it would consider its capacity to produce the vaccine onshore, the company has made clear its first priority is completing the 50 million doses of AstraZeneca.
As the pandemic has progressed, Associate Professor Griffin says one thing is certain: Australia is going to need a number of candidates to ensure there are safe and effective vaccines available for everyone in the population.
‘These vaccines will obviously have us in a good position, and the fact that we’re going to also have Novavax, I think, is really fortuitous for our country, and demonstrates that the deals done before we had any robust data to actually secure three successful candidates out of four is actually quite amazing,’ he said.
‘But it may well be that we need additional vaccines in the future to address other challenges – maybe an oral vaccine or an intranasal vaccine or something that potentially is longer lasting or better suited to different variants, for example.
‘The vaccines for COVID will continue to evolve over time.’
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