Novavax candidate may prove best long-term solution for Australia

Matt Woodley

14/01/2021 5:01:51 PM

While debate swirls around the first two vaccines set to be used in the rollout, NVX-CoV2373 comes with potential advantages.

Shopping cart holding Novavax vaccine vials.
Novavax is expected to release interim phase 3 results within weeks.

Last Friday, the Australian Government finalised a purchase agreement to secure 51 million doses of Novavax’s COVID-19 vaccine candidate NVX-CoV2373.
The ‘subunit vaccine’, which Australia initially sourced 40 million doses of before adding another 10 million to supplement the shortfall from the University of Queensland’s scrapped ‘molecular clamp’ candidate, is in the final stages of phase 3 clinical trials in the US, UK and Mexico.
It has also recently completed a phase 2b trial in South Africa, the results of which are expected within the next fortnight, while an earlier phase 1/2 trial elicited antibody responses numerically superior to those seen in blood samples drawn from mostly symptomatic COVID-19 patients.
Infectious diseases physician and microbiologist Associate Professor Paul Griffin, who oversaw the Australian arm of the phase 1/2 trial, told newsGP the available data looks ‘very promising’ and is a cause for ‘genuine optimism’.
‘The main thing to say is we need to wait to get the phase 2b and the phase 3 data, but obviously if  the surrogates’ immunogenicity that was generated in the phase 1 study proves to correlate with clinical protection, then we’ll be in a really good position,’ he said.
‘I’m really looking forward to seeing the data to show that.’
The ongoing randomised, placebo-controlled trials will enrol approximately 30,000 people in the US and Mexico across 115 sites, and an additional 15,000 in the UK. The US and Mexico trials have been grouped into two cohorts – those aged 18–64 and 65+ – while trial organisers have emphasised recruiting people who are at higher risk of severe COVID-19 disease, including different ethnicities and people who have underlying health conditions such as obesity, chronic kidney disease or diabetes.
‘My understanding is that while we haven’t seen the interim results yet, they should be forthcoming fairly soon,’ Associate Professor Griffin said.
‘Novavax has intentionally selected a very diverse array of participants for these studies, particularly representing vulnerable populations, such as Indigenous people and a wide variety of other ethnicities, elderly, and even some cohorts with HIV.
‘That’s really useful, because it shows the vaccine to be broadly applicable if it proves effective, in all of those cohorts.’
The HIV cohorts were included in the 4422 people who participated in the phase 2b South Africa trial, which ran from August to November and should have the added benefit of being tested against the new, more infectious, 501.V2 variant that emerged on the Eastern Cape in August and may decrease the efficacy of some vaccines.
‘Obviously, given the widespread situation now with the UK variant, it’s very likely that we’ll see people enrolled in the [phase 2b and phase 3] studies with both of those,’ Associate Professor Griffin said.
‘It’ll be really interesting to see if they’re protected – which is very likely, but definitely useful to show that in the phase 3 studies.’

Associate Professor Griffin says having different types of vaccine candidates is a ‘huge advantage’. 

Another benefit for Australia in particular, is the fact that Novavax’s candidate relies on a different mechanism to generate immunity than the Pfizer/BioNtech mRNA vaccine and AstraZeneca’s viral vector candidate, AZD1222.
Associate Professor Griffin says this is a ‘huge advantage’ for Australia’s vaccine program overall, as it is ‘very likely’ there will not be a single vaccine that is rolled out everywhere.
‘Even within our country, we’re going to need a range of different vaccines that cater potentially for different populations or different comorbidities, for example, and different environments,’ he said.
‘While we see the mRNA vaccines are highly efficacious, they’re not as broadly applicable because of the extreme cold chain.
‘[NVX-CoV2373] is a vaccine that looks to be very well tolerated, but also very temperature stable. So for a country with conditions like ours, it may well be that the Novavax vaccine is actually the one that that we use the most in the end.
‘A lot less infrastructure is required to use this vaccine … so that’s going to mean, hopefully, they can be much easier to distribute through GP clinics.’
If all goes well, the vaccine could become available in Australia as early as April – although that will be dependent on the success of the ongoing trials, along with it being approved by the Therapeutic Goods Administration.
Associate Professor Griffin says he has great faith in this process, not just in terms of Novavax, but also the registering of Pfizer/BioNTech and AstraZeneca/Oxford University’s candidates.
‘The key here is that we should just have faith in our regulatory system. They’re obviously paying a lot of attention to a lot of data that’s not yet in the public domain,’ he said.
‘AstraZeneca is doing a great job of essentially supplying data in real time to a number of different regulatory bodies, and despite calls to hasten that process it is still holding firm and making sure it applies all of the usual checks and balances.
‘People are trying to interpret very small snippets of data and then question whether it’s the right thing to do. We should leave that to the experts who do this for a living and if any of these vaccines are approved, then we should definitely support their use.’
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