Tens of millions of doses of the Novavax vaccine will now be produced and packaged in north-east England, the prime minister has announced.
Boris Johnson said a deal had been agreed with GlaxoSmithKline (GSK) to bottle 60 million doses at its facility in Barnard Castle, County Durham.
GSK said it hoped the "fill and finish" process can begin as early as May.
In January, it was announced the vaccine would be manufactured at the Fujifilm plant in Billingham.
Novavax is currently being assessed by the Medicines and Healthcare products Regulatory Agency.
The biotech company behind it, also called Novavax, recently announced its vaccine was 86% effective against the Kent variant of Covid-19 and 96% effective in preventing cases caused by the original strain.
Mr Johnson said: "I'm delighted by GSK's investment, which shows the strength of UK manufacturing, and will further boost our vaccine rollout.
"The Vaccines Taskforce has worked hand in glove with business to successfully deliver vaccines to the whole of the UK, and this agreement will continue to support our approach.
"We remain on track to offer a first jab to all over 50s by 15 April, and all adults by the end of July, and I want to once again encourage everyone to come forward for a vaccine when you're called."
The news that the Novavax vaccine is going to go through a process known as fill and finish in the UK is an interesting development.
Fill and finish is the process by which vaccines are packaged up in vials, ready to be sent out to vaccination clinics.
The original plan was for this to be done in Europe once the vaccine product was manufactured by plants in the north east.
But a deal has been struck with drug firm GSK to do that here.
Officially, the government is saying that it is all part of their investment in the British life science industry.
But given the threats from Europe about restricting exports of vaccines, it begs all sorts of other questions too.
The north east plants have already started manufacturing the 60m doses ordered by the government. If it gets approval by the regulator - expected in the coming weeks - supplies could be available in June.
Roger Connor, president of GSK vaccines, said: "GSK is delighted to support Novavax and the UK Vaccines Taskforce with this manufacturing arrangement for the UK and our Barnard Castle facility is now undertaking the rapid preparation work required to manufacture up to 60 million doses of this vaccine.
"We have ensured that we can deliver these volumes without impacting supply of our other vital medicines and vaccines, and without disruption to the other Covid-19 collaborations GSK is engaged in globally."