The UK has reached a "hugely significant milestone" in its coronavirus vaccination programme, with 10 million adults now having received their first dose.
Health Secretary Matt Hancock thanked everyone who had played a part in the achievement, with the UK leading most of the world with its vaccine rollout.
Reaching the milestone means 15% of UK residents have now been given their first coronavirus jab.
The health secretary wrote on Twitter: "10 MILLION people have now received their first dose of the COVID vaccine.
"This is a hugely significant milestone in our national effort against this virus.
"Every jab makes us all a bit safer - I want to thank everyone playing their part."
It means the UK looks likely to reach its target of vaccinating the 15 million people most vulnerable to coronavirus by mid-February.
It is not yet clear how many adults have received their second dose of the vaccine, but Boris Johnson is likely to provide an update at a press conference scheduled for 5pm.
As of February 1, 496,796 people had received their second dose, but that number is likely to have since increased.
While having 15% of the population vaccinated is welcomed, it is a long way from a proportion that would allow the UK to achieve herd immunity.
Last week, when the UK had vaccinated 10% of its population. Dr Susan Hopkins, Covid-19 strategic response director at Public Health England, said Britain was still "far away" from achieving herd immunity.
She told a Downing Street press conference: "The big job here is to roll out the vaccination to those individuals first of all, to those who are high risk of death and hospitalisation and then to the rest of the population.
"Once we have done that, then we will have herd immunity.
"We should not be focusing on getting infection and the consequences of this infection, getting us out of this right now."
Mr Hancock earlier hailed another significant vaccine breakthrough, after a study found a single dose of the Oxford vaccine may reduce transmission of Covid by up to 67%.
The data provides a major boost to the UK’s policy of delaying the second jab for up to 12 weeks.
Before these results, little was known about how effective the Covid-19 vaccines were at preventing transmission of the disease. Health Secretary Hancock hailed the "encouraging" study's findings as "absolutely superb", adding it "reinforces our confidence that vaccines are capable of reducing transmission and protecting people from this awful disease". Mr Hancock said the "report shows the Oxford vaccine works and works well", though the data is still pending peer review.
The findings indicate that those who have been vaccinated are not only protected from the disease, but that they are not likely to pass on the virus to anyone.
It also suggests the vaccine eliminates severe illness, as none of those in the study were admitted to hospital with coronavirus.
He told ITV's Good Morning Britain the study "demonstrates that the vaccine protects you and it helps cut the transmission of the disease across the whole community".
"It just shows that the strategy has been right of backing those vaccines"He added: "The other finding in this report is that the with the 12 week gap between first and second dose, you actually get stronger protection than you do with the shorter gap."
Prime Minister Boris Johnson said the data from the study was “really encouraging”.
On Twitter, he said the "new study today shows the Oxford/AZ vaccine provides significant protection against the virus".
Former chair at the Faculty of Pharmaceutical Medicine, Dr Gillies O'Bryan-Tear said the results, which have yet to be peer reviewed, were the first definitive estimate of the impact of vaccination on transmission rates.
"If the effect on transmission is confirmed for the Pfizer vaccine too, this would be a very positive," he said.
"If these vaccines reduce transmission to the extent reported, it will mean that the easing of social restrictions will be enabled sooner, than if we have to wait for herd immunity - which may never in fact be achieved because of insufficient vaccine population coverage."
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