Novavax is absent from Australia’s 2021 vaccination schedule. But it could be a useful booster later on


Cassandra Berry, Murdoch UniversityNovavax recently released excellent results from phase 3 clinical trials, finding its COVID-19 vaccine demonstrated 90.4% efficacy overall after two doses given three weeks apart.

The results, from close to 30,000 people in the United States and Mexico, found the vaccine demonstrated 100% protection against moderate and severe COVID-19, and was highly protective against circulating variants of interest and concern. It also has a good safety profile.

It’s important to note these results came directly from Novavax in a press release, and we’re still waiting to see the data published in a peer-reviewed journal. Once this happens, it’s likely Novavax will apply for approval from medical regulators around the world.

But this process will take a few months. The Therapeutic Goods Administration has said it doesn’t expect to receive the final data it needs to approve the vaccine until September. And in the COVID Vaccination Allocation Horizons, information the government released this week setting out vaccine allocation until the end of 2021, Novavax is not mentioned.

So by the time Australia is ready to deliver Novavax — the country has 51 million doses on order — we may well have completed most of the vaccine rollout with the AstraZeneca, Pfizer and Moderna vaccines. The situation will be similar in other countries, such as the United States.

However, that doesn’t mean Novavax won’t play an important role in Australia’s fight against COVID-19.

How does Novavax work?

Novavax is designed using protein-based technology. This is different from the AstraZeneca vaccine, which is a viral vector vaccine, and Pfizer and Moderna, which use mRNA technology.

Novavax works by introducing a part of the SARS-CoV-2 virus — the spike protein — to the immune system. The spike protein used is made in insect cells and doesn’t contain any live components of the virus. It can’t replicate or cause COVID-19.

To help the vaccine generate a stronger protective response, it uses an adjuvant, which is a molecule that boosts the immune system. The adjuvant Novavax uses is based on saponin, a natural extract from the Chilean soapbark tree.

An illustration of SARS-CoV-2.
COVID-19 vaccines work by targeting the spike protein, a protein on the surface of SARS-CoV-2.
Shutterstock

In some countries, Novavax could be used as an initial COVID vaccine. It will be relatively easy to distribute because it can be stored at regular fridge temperatures.

In other countries where most people will have already received two vaccine doses by the time Novavax becomes available, the vaccine could be used as an annual booster — on its own or as a supplement in formulated vaccines.




Read more:
What is Novavax, Australia’s third COVID vaccine option? And when will we get it?


A potential booster

Let’s say you’re writing a book. You write your first draft — that’s the first dose of vaccine. Then you edit and refine the final draft — that’s the second dose. You could say annual booster vaccines are like updated editions. Perhaps the original book is also translated into different languages, just as boosters could cover viral variants around the world.

In slightly more scientific terms, after the first vaccine dose, certain cells in our immune system (normal B cells) are activated and produce a primary antibody response. After the second vaccine dose, a slightly different flavour of immune cells (memory B cells) mount a stronger antibody response more rapidly.

But this immune memory can wane over time. Boosters may be needed to enhance immune memory responses to the SARS-CoV-2 spike protein in people who have previously been vaccinated against COVID-19.

Boosters could also be important as new variants emerge. Vaccines can often be reformulated to protect against new viral variants when original formulations aren’t working as well.

So even if Novavax isn’t the first or second COVID vaccine in our arms, it could be an important tool in our arsenal as we continue to navigate the pandemic.

A person with a bandaid on their upper arm.
Novavax could potentially be used as a booster vaccine down the track.
Shutterstock

What about in combination with the flu shot?

Novavax has recently revealed the efficacy of its COVID vaccine was roughly the same in a study where an influenza vaccine was administered simultaneously. This data, although yet to be peer-reviewed, signals Novavax could potentially be given alongside the annual flu shot.

In the future, we could even have the flu shot and Novavax combined in one vaccine. Novavax has designed and is currently testing a vaccine which combines SARS-CoV-2 and influenza spike proteins (called a multivalent vaccine).




Read more:
Can I get AstraZeneca now and Pfizer later? Why mixing and matching COVID vaccines could help solve many rollout problems


SARS-CoV-2 is rapidly evolving and we need to future-proof Australia against viral variants. As our knowledge of COVID-19 builds, we must develop strategies for more robust protection.

Rather than a fast sprint, our immune systems likely need to be primed for an ultra-marathon. Thinking about vaccines beyond the “first wave” of vaccination will be key.The Conversation

Cassandra Berry, Professor of Viral Immunology, Murdoch University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What is Novavax, Australia’s third COVID vaccine option? And when will we get it?


Jamie Triccas, University of SydneyAs AstraZeneca is no longer the preferred vaccine for Australian adults under 50, attention is turning to what other COVID-19 vaccine options are in our arsenal.

The federal government has ordered 40 million doses of the Pfizer vaccine, which will become the mainstay of the rollout, while AstraZeneca will continue to be administered for people over 50 in the current phase 1B.

The federal government also this week ruled out using Johnson & Johnson’s one-shot vaccine.

But Australia does have a deal for a third vaccine, by US biotech company Novavax. The government has ordered 51 million doses of this vaccine, though it’s yet to be approved by Australia’s drug regulator, the Therapeutic Goods Administration (TGA), which is expected to make a decision in the third quarter of the year.

At this stage, Novavax would be made offshore and imported, although Melbourne-based biotech CSL can make the vaccine if requested by the federal government.

How does the Novavax vaccine work?

The Novavax vaccine is given as two doses, similar to the Pfizer and AstraZeneca shots already being used in Australia.

It can be stored for up to three months at fridge temperature, which differs from the Pfizer mRNA vaccine which needs to be kept at ultra-low temperatures. In saying that, the TGA said last week the Pfizer vaccine can be stored at normal freezer temperatures for two weeks during transport, and at fridge temperatures for five days — though must still be kept ultra-cold after transport and in the long-term.

A graphic comparing Australia's three vaccine options
Comparing Australia’s three COVID-19 vaccine options.
Jamie Triccas, made with BioRender, CC BY-ND

The vaccine also uses a different technology to the Pfizer and AstraZeneca vaccines. It’s a “protein subunit” vaccine; these are vaccines that introduce a part of the virus to the immune system, but don’t contain any live components of the virus.

The protein part of the vaccine is the coronavirus’ “spike protein”. This is part of the other COVID-19 vaccines in use but in a different form.




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New coronavirus variant: what is the spike protein and why are mutations on it important?


The Novavax vaccine uses a version of the spike protein made in the lab. The spike proteins are assembled into tiny particles called “nanoparticles” which aim to resemble the structure of the coronavirus, however they cannot replicate once injected and the vaccine cannot cause you to get COVID-19.

In order for these subunit vaccines to generate strong protective responses, they need to include molecules that boost your immune system, called “adjuvants”. The goal of these adjuvants is to mimic the way the real virus would activate the immune system, to generate maximum protective immunity.

Novavax includes an adjuvant based on a natural product known as saponin, an extract from the bark of the Chilean soapbark tree.

How effective is the vaccine compared to those already in use in Australia?

The interim data from phase 3 testing, released in March, was very encouraging. When tested in the UK in a clinical trial including more that 15,000 people, the vaccine was 96% effective at preventing COVID-19 disease for those infected with the original strain of the coronavirus.

This compares well to the Pfizer vaccine, with an efficacy of 95%, and recent data from AstraZeneca demonstrating 76% efficacy against COVID-19.

The Novavax vaccine is also safe. In early clinical testing the vaccine caused mainly mild adverse events such as pain and tenderness at the injection site, and no serious adverse reactions were recorded. In the larger trials, adverse events occurred at low levels and were similar between the vaccine and placebo groups.

What about protection against variants?

In the UK trial, the vaccine maintained strong protection against disease in people infected with the B.1.1.7 “UK variant”, demonstrating 86% efficacy.

This is good news because the B.1.1.7 variant is now dominant in many European countries, is more transmissible and deadly than the original SARS-CoV-2 virus, and is responsible for most of the cases that have arisen recently in Australia.




Read more:
The UK variant is likely deadlier, more infectious and becoming dominant. But the vaccines still work well against it


Less encouraging is protection against the B.1.351 variant first identified in South Africa, which can evade immunity that developed in response to earlier versions of the virus. The efficacy of Novavax’s shot dropped to 55% in protecting against COVID-19 symptoms from this variant. Protection against severe disease however was 100%, indicating the vaccine will still be important in reducing hospitalisation and death due to this variant.

Novavax, along with the other major vaccine companies, are developing booster vaccines to target the B.1.351 variant. Novavax are planning to test a “bivalent” vaccine, which targets two different strains, using the spike protein from both the original Wuhan strain and the B.1.351 variant.




Read more:
Why we’ll get COVID booster vaccines quickly and how we know they’re safe


The Conversation


Jamie Triccas, Professor of Medical Microbiology, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.