New Zealand's vaccine rollout so far has relied entirely on a single supplier, but that appears set to change.
Millions of doses of a vaccine developed by Novavax are expected to arrive in the first quarter of 2022, COVID-19 Response Minister Chris Hipkins told Stuff on Wednesday. Whether it will be used as an alternative to the Pfizer-BioNTech jab, as a booster or both isn't yet known.
Trails to date have found NVX-CoV2373, as it's called, is highly effective against early strains of the SARS-CoV-2 virus, and perhaps less likely to cause side effects than the Pfizer jab.
Here's what you need to know.
What is Novavax?
Novavax is an American company formed in the 1980s to develop experimental vaccines that has never before brought a successful vaccine to market. Despite this, in 2020 it got a massive contract from the Trump administration to develop a vaccine against SARS-CoV-2 as part of its 'Warp Speed' effort.
It has previously worked on vaccines for Ebola, Zika, RSV and influenza, before pivoting to COVID-19 in 2020.
What is its COVID-19 vaccine?
NVX-CoV2373 is a "protein-based vaccine candidate engineered from the genetic sequence of the first strain of SARS-CoV-2", according to Novavax. Work on it began in January 2020, around the same time as BioNTech (which would later team up with Pfizer) and Moderna, after the virus' genetic code was sequenced and made available.
The gene for the virus' spike protein is inserted into an insect virus which is used to infect moth cells. The cells produce new spike proteins, which are harvested and put on nanoparticles. Once injected, our immune systems recognise the spike proteins as foreign and mount a defence.
Novavax's vaccine uses what's known as an adjuvant to help boost the immune response - in this case, saponin, a plant-derived chemical.
How is this different to Pfizer's?
The basic technology behind NVX-CoV2373 has been used since the mid-1980s, The Atlantic reported, in vaccines for hepatitis B and whooping cough.
Pfizer and Moderna's vaccine uses a new type of vaccine technology called mRNA - the first to have made it out of the trial phase. Their vaccines don't contain any viral material at all, instead using a piece of code which teaches our cells how to make the spike proteins themselves.
How does Novavax's vaccine stack up? Does it work against variants like Delta?
In its trials, NVX-CoV2373 performed very well - it offered 90 percent protection against symptomatic infection and not a single person amongst those who received it in the phase 3 trial developed severe disease.
It also worked well against the Alpha variant, which was dominant in the US and Mexico at the time the trial took place. It didn't do so well against Beta in South Africa when it came to stopping infection, but it still successfully prevented serious illness.
Real-world data on its efficacy against Delta isn't available yet, but Novavax's latest lab tests suggest it offers some protection - whether it's more or less than the reduced efficacy of the already widely used vaccines remains to be seen.
"All these vaccines were tested at different times against different variants with different outbreaks and different contacts with different populations," Ashish Jha, dean of the Brown University School of Public Heath, told NPR in June after its efficacy results were published. "The fundamental question I ask when I look at all these vaccines is, are they going to prevent people from getting really sick and dying? And all of these vaccines do that beautifully."
As for whether it works as a booster when paired with other vaccines also isn't known. Australia has ordered tens of millions of doses to be used as boosters already. Research so far into mixing vaccines has been mixed, at least when it comes to first and second doses. Some research has suggested using different kinds of vaccines gives the body more ways to fight an infection, while others have said there's far more research backing a two-dose regimen of the same vaccine.
What about side-effects?
The Novavax vaccine appeared to trigger fewer mild-to-moderate side effects in its trials than Pfizer. But - as we've discovered with the rapid rollout of Pfizer, Moderna, AstraZeneca and Janssen vaccines across the world, some serious - even deadly - side effects are so rare they don't show up until millions of people have been injected.
The known side effects to date are typical of any vaccine - headaches, muscle pain and tiredness amongst them.
"Protein-subunit vaccines are considered the safest form of vaccines, based on a widely used technology," University of California Berkeley head of infectious diseases Lee Riley said in June.
What are some other advantages and disadvantages?
Novavax says its vaccine can be delivered alongside an influenza vaccine, which isn't recommended for the Pfizer jab.
There has been widespread misinformation about mRNA vaccines, including false claims they can alter patients' DNA. It's been suggested some people hesitant to get an mRNA vaccine might be more likely to accept a vaccine based on more traditional technology, like that made by Novavax.
It takes a lot longer to make the Novavax vaccine than the mRNA offerings - it reportedly takes just minutes to produce as much synthetic mRNA vaccine as traditional techniques produce in a week. Novavax expects to be able to make 150 million doses a month by the end of 2020 - less than the 250 million a month Pfizer expects to make this year.
People who have a serious reaction to the contents of the Pfizer vaccine - typically the lipid nanoparticle it comes in - might fare better with the Novavax vaccine.
Novavax doses can be stored long-term at typical fridge temperatures, making it easier to store and transport than the Pfizer jab, which needs to be kept in specialised ultra-cold freezers until it's ready to be deployed.
Why has it taken so long?
New Zealand signed a provisional deal with Novavax in 2020, alongside orders from AstraZeneca, Janssen and Pfizer. After seeing the rapid rollout and success of the Pfizer jab in the US and Israel, New Zealand opted to use it exclusively for the initial rollout.
Novavax is a much smaller company than some of the other manufacturers. BioNTech - a small German company - realised early on its mRNA technology might work against COVID-19, and sought the assistance of pharma giant Pfizer in March 2020. Moderna teamed up with the US National Institutes of Health.
Novavax began its in-person research the week as BioNTech, The Atlantic reported, but didn't team up with a larger partner to speed things along.
Earlier this year there was speculation Novavax could team up with Merck, after the latter's attempt at developing a COVID-19 vaccine was abandoned. It eventually signed up with GlaxoSmithKline, another giant that failed to develop its own jab. It's also cut deals with other drugmakers in countries like Japan, Poland and India.
Novavax has repeatedly delayed seeking approval from US health authorities, most recently in early August. Medsafe here in New Zealand says it's currently under evaluation, awaiting more data from Novavax. An application in the UK is expected in September, Stuff reported, with Australia shortly after.
Hipkins on NZ's Novavax rollout
Asked about Novavax in Wednesday's coronavirus press briefing, COVID-19 Response Minister Chris Hipkins said it would have to go through several steps before it was put to use here.
MedSafe approval was a really integral part of the process, he said - but just one of these steps.
After that, Cabinet would have to weigh up whether to use it, where and by whom it would be used, and all the logistical dilemmas.
"But I can say we have a really good vaccination network now, that we will be able to use for follow-up vaccinations," he said.
"Whether that's booster shots or another whole round of vaccination that's required… we'll have systems that'll be in place to do so."