Covid vaccines cut risk of serious illness by 80% in over-80s.
The Public Health England data showed the effect kicked in three to four weeks after vaccination.
It was supported people aged over 80 who were the primary to receive the jab.
Government scientists hailed the result, but stressed that two doses were needed for the simplest protection.
It comes after similar findings were published by Scottish health authorities last week, which they hailed as “spectacular”.
Health Secretary Matt Hancock told a Downing Street briefing on Monday the newest vaccine results were “very strong”.
He added: “They can also help to elucidate why the amount of Covid admissions to medical care units among people over 80 within the UK have dropped to single figures within the last few weeks.”
Also speaking at the press conference , England’s deputy chief medic – Prof Jonathan Van-Tam – said the info offered a glimpse of how the vaccine programme “is getting to hopefully take us into a really different world within the next few months”.
But he said it had been “absolutely critical” that second doses “are still a part of the course of immunisation against Covid-19 and no less important”.
Prof Van-Tam stressed there was a “significant likelihood” that a second dose of a vaccine would “mature your immune reaction , possibly make it broader and almost certainly make it longer than it might rather be in reference to a primary dose only.”
More than 20 million people within the UK have had their first dose of a vaccine – over a 3rd of the adult population.
Meanwhile, another 104 deaths within 28 days of a positive coronavirus are reported within the UK, and an extra 5,455 new cases, consistent with the newest figures.
The PHE data, which has not been peer reviewed, also suggested the Pfizer vaccine, which started being unrolled a month before the AstraZeneca vaccine, results in an 83% reduction in deaths from Covid. This was supported people over the age of 80 who had died.
The data also showed vaccination cuts the danger of individuals over 70 developing any Covid symptoms by around 60%, three weeks after an initial dose.
Prof Van-Tam said the choice to offer the AstraZeneca vaccine to older people was “clearly vindicated”.
Some European nations have refused to offer it to the over 65s because data from the trials was mainly on its effect among younger adults.
Prof Van-Tam said the judgement made by the united kingdom authorities was that it had been simply “not plausible” the vaccine would only work on younger adults.
He said other countries would doubtless be “very interested” within the data beginning of the united kingdom .
Dr Mary Ramsay, Public Health England’s head of immunisation, said there was growing evidence that the vaccines were working to scale back infections and save lives.
“While there remains far more data to follow, this is often encouraging and that we are increasingly confident that vaccines are making a true difference,” she said.
However, more evidence is required to understand how well the vaccines protect against the Brazil variant that has recently been identified within the UK.
This variant features a mutation – E484 – that would reduce a number of the effectiveness of the vaccines.
It was announced on Sunday that six new variant cases – three in England and three in Scotland – had been found through testing.
Health officials are ready to contact about one among these people. The whereabouts of the remaining individual is unknown as they didn’t complete their test registration card.
It has prompted an appeal for anyone without a result from a test on 12 or 13 February to return forward immediately by calling 119.
The health secretary has denied that delays in imposing quarantine hotel measures on travellers to the united kingdom put lives in danger , as officials still seek the individual.
Mr Hancock said there was “no evidence” the infected person had not followed home quarantine rules.
Earlier, Prime Minister Boris Johnson said the united kingdom has “one of the toughest border regimes anywhere within the world for stopping people coming in to the present country who may have variants of concern”.