The Prime Minister and Health Secretary have welcomed the results from a trial of a vaccine which offers 89% protection against Covid-19.
The Novavax jab, which will be manufactured in Stockton-on-Tees, appears to be effective against both the original strain of coronavirus and a mutant strain first identified in Kent.
It has also shown around 60% effectiveness against the South African strain of coronavirus, which has been worrying scientists due to concerns vaccines may not work against it.
The UK has secured access to 60 million doses of the new vaccine, which could be available in the second half of this year if it is approved by the medicines regulator.
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 (NIHR).
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 first identified in Kent circulating widely.
The UK arm 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 Novavax jab.
This part of the trial showed the jab was 89% effective against Covid-19.
More than half of cases related to the UK strain of the virus, with the vaccine offering 86% protection against this particular strain.
Against the original strain that has circulated since the start of the pandemic, the vaccine was 96% effective.
Overall, data from more than 20,000 people, including a trial in South Africa, has now been reported in full.
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%.
Health Secretary Matt Hancock said: “This is positive news and, if approved by the medicines regulator, the Novavax vaccine will be a significant boost to our vaccination programme and another weapon in our arsenal to beat this awful virus.
“I’m proud the UK is at the forefront of another medical breakthrough and I want to thank the brilliant scientists and researchers, as well as the tens of thousands of selfless volunteers who took park in clinical trials.
“The NHS stands ready to roll this vaccine out as quickly as possible to those most at risk if it is authorised.”
Boris Johnson thanked thousands of study volunteers “who made these results possible”.
Vaccines minister Nadhim Zahawi said he was “particularly thrilled to see such positive results” having taken part in the trial personally.
“I want to thank the thousands of trial volunteers, without whom these results would not have been possible,” he added.
The trial was carried out in conjunction with the UK Government’s Vaccine Taskforce, with its chairman Clive Dix saying in a statement: “These are spectacular results, and we are very pleased to have helped Novavax with the development of this vaccine.
“The efficacy shown against the emerging variants is also extremely encouraging. This is an incredible achievement that will ensure we can protect individuals in the UK and the rest of the world from this virus.”
The jab has an advantage over those from Pfizer/BioNTech and Moderna in that it can be stored in a regular fridge rather than needing ultra-cold storage.
Professor Peter Openshaw, from Imperial College London, said the findings showed the jab “gives high levels of protection”.
However, he said the 60% finding for the South African variant was a “concern” due to suggestions that prior infection with earlier variants of Covid-19 may not completely protect against subsequent infection by the South African variant.
Kate Bingham told the BBC: “It’s a fantastic result because it shows that the Novavax vaccine is effective against the UK variant as well as the South African variant and has shown phenomenal efficacy, and it’s made in Teesside.
“So not only have we trialled the vaccine to show it is safe and effective, but we are also making it too.
“So we will be able to save lives in the UK.”