A vaccine from Novavax, of which the UK has secured 60 million doses, has been shown to be 89% effective in preventing Covid-19.
Here's what we know and don't know about the jab so far.
How effective is the jab?
It was shown to be 89.3% effective at preventing coronavirus in participants in its Phase 3 clinical trial in the UK, which involved more than 15,000 people aged between 18-84, of which 27% were older than 65, Novavax said.
How many doses of the Novavax vaccine has the UK ordered?
The UK has secured 60 million doses of the Novavax jab – to be produced on Teesside – which is believed to offer protection against the new UK and South African variants.
How does the vaccine work?
The Novavax vaccine works like other vaccines by teaching the immune system to make antibodies to the coronavirus spike protein.
Researchers inserted a modified gene into a virus, called a baculovirus, and allowed it to infect insect cells.
Spike proteins from these cells were then assembled into nanoparticles which, while they look like coronavirus, cannot replicate or cause Covid-19.
These nanoparticles are then injected into the body via the vaccine where the immune system mounts an antibody response.
If the body encounters coronavirus in the future, the body is primed to fend it off.
Are there advantages of the Novavax vaccine?
Yes. While the jabs from Pfizer/BioNTech and Moderna need to be kept at ultra-low temperatures, the Novavax jab is stable for up to three months in a normal fridge.
The jab should be available in the second half of this year and is being manufactured in Teesside.
Was the jab tested in the UK?
Yes. More than 15,000 people in the UK took part in the clinical trial, which was supported by the UK National Institute for Health Research.
Some 27% of those in the UK were over the age of 65.
The study assessed how effective the vaccine was when transmission of Covid-19 was high in the UK, and with the variant strain identified in the UK circulating widely.
The analysis, based on the first 62 cases of Covid-19 identified in the trial, reported 56 cases in people given a placebo (dummy) vaccine while six cases were in those given the vaccine.
More than 50% of cases related to the UK strain of the virus, with the vaccine offering 86% protection against this strain.
Against the original strain that has circulated since the start of the pandemic, the vaccine was 96% effective.
What about the South Africa strain?
Data from more than 20,000 people, including a trial in South Africa, has now been reported.
In the South African arm of the trial, where most cases of Covid-19 were the South African strain, the jab was 60% effective in preventing mild, moderate and severe coronavirus among those without HIV.
Including the HIV positive participants, whose immune systems are compromised, overall the protection was just over 49%.
Scientists continue to be concerned about the South African strain of the virus and one that emerged in Brazil, with the expectation that these strains will not work as well with current vaccines.
Novavax plans to immediately begin development on a vaccine specifically targeted to the South African variant.
How has this come about so quickly?
The timetable for developing and approving a Covid vaccine has been condensed owing to the coronavirus crisis.
What is the usual process for developing a vaccine?
Traditionally, vaccine development takes several years and includes various processes, including design and development stages followed by clinical trials – which in themselves need approval before they even begin.
The trials take place in three sequential stages – also known as phases. The research will show whether a vaccine generates antibodies but also protects people from disease. They will also identify any safety issues.
Once the trials are complete, the information gathered by researchers is sent to regulators for review.
This is thoroughly analysed by clinicians and scientists before being approved for widespread use.
Then, after approval from regulators, people can start to receive the vaccine.
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When could Britons start receiving the new jab?Regulators have been carrying out “rolling reviews”, which means that instead of going through reams of information at the conclusion of the trials, they have been given access to the data as the scientists work.
A rolling review of the vaccine data started several months ago.
This means regulators can start to look at scientific data earlier than they traditionally would do, which in turn means the approval process can be sped up.
Regulators sometimes have thousands of pages of information to go over with a fine-tooth comb – which understandably takes time.
Once all the data available on the vaccine is submitted, MHRA experts will carefully and scientifically review the safety, quality and effectiveness data – how it protects people from Covid-19 and the level of protection it provides.
After this has been done, advice is sought from the Government’s independent advisory body, the Commission on Human Medicines (CHM).
Haven’t pharmaceutical companies already started making vaccines?
Yes. Usually large-scale production and distribution begins only after regulatory approval. But in the case of Covid-19 vaccines, pharmaceutical firms have begun manufacturing before final approval had been granted – taking on the risk that they may be forced to scrap their work.