The UK government welcomed results from Novavax vaccine trials that show it offers 89 per cent protection against coronavirus.
The product is due to be manufactured in Britain and appears to be effective against the original strain of coronavirus and a mutant strain first identified in Kent, south-east England.
The Novavax drug showed about 60 per cent effectiveness against the strain of Covid-19 first identified in South Africa, which has been problematic for scientists owing to concerns it may evade vaccines.
The UK secured access to 60 million Novavax doses, which will be available in the second half of this year if the vaccine is approved by the medicines regulator.
More than 15,000 people in the UK took part in the clinical trial, 27 per cent of whom 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 first identified in Kent circulating widely.
Prof Paul Heath, Novavax clinical trial chief investigator, said the data showed science was able to adapt to mutations.
"The UK variant can successfully be prevented with this vaccine. Yes, the South African is more difficult," he told the BBC's Radio 4 Today programme on Friday.
"But I think all of the technologies we have seen mean we can adapt at pace, so we can keep up and get ahead of the virus."
Kate Bingham, the former head of the UK's vaccine task force and the person who placed the orders for Novavax doses, said that she was delighted but the next goal was to find an easier way to administer vaccines.
“Frankly, two injections delivered by healthcare professionals is not a good way of delivering vaccines," she said. "We need to get vaccine formats that are much more scalable and distributable. So whether they’re pills or patches or nose sprays, we need to find better ways of delivering vaccines."
Ms Bingham said that collaboration with the European Union would help with this.
The UK analysis, based on the first 62 cases of Covid-19 identified in the trial, reported 56 cases in people given a placebo vaccine while only six cases were found in those given the Novavax shot. This part of the trial showed the drug to be 89 per cent effective against Covid-19.
More than half of cases related to the newer UK strain of the virus with the vaccine offering 86 per cent protection against that particular mutation. Against the original strain, the vaccine was 96 per cent effective.
Overall data from more than 20,000 people, including a trial in South Africa, has now been reported in full.
UK Prime Minister Boris Johnson, under fire this week after the UK officially exceeded the 100,000 Covid deaths mark, welcomed the results on Twitter:
Health Secretary Matt Hancock was similarly upbeat, tweeting:
The trial was carried out in conjunction with the UK government’s vaccine task force, whose chairman Clive Dix called the results spectacular.
The Novavax vaccine can be stored in a regular fridge, unlike the ultra-cold storage required by rival drugs such as those produced by Pfizer/BioNTech and Moderna.
Prof Peter Openshaw, a scientist from Imperial College London, threw his weight behind the findings too, saying they showed the jab “gives high levels of protection”.