Vaccines appear to cut Covid-19 transmissions and infections by two thirds, according to the first "real world data" examining the impact of the jabs, The Daily Telegraph can disclose.
Key data being handed to UK Prime Minister Boris Johnson as he finalises a road map out of lockdown show that just one dose of either the Oxford or Pfizer vaccine has such an effect on all age groups.
Johnson and his scientific advisers are expected to examine the new evidence showing the impact of the jabs on transmission, infection, hospitalisation and deaths.
Whitehall sources said the studies would be crucial to deliberations over Britain's way out of lockdown - but called the findings "very encouraging".
Separate data showed Covid cases were falling most rapidly among the oldest, with care-home outbreaks almost halving in a week. The statistics appear to vindicate Britain's strategy of vaccinating in age order, with cases among those over 80 falling 38 per cent in seven days.
On Monday (UK time) Johnson publishes his road map, which is expected to start with the return of schools from March 8, ahead of any relaxation of rules over outdoor socialising and the reopening of shops, pubs and restaurants.
It comes amid pressure from Tory backbenchers for a speedy easing of lockdown restrictions. Behind the scenes, Matt Hancock, the Health Secretary, is among those understood to be pushing for an earlier timetable.
Last week he told The Telegraph that drugs and vaccines "represent "our way out to freedom", having earlier said Britain could enjoy a "happy and free" summer after millions had been jabbed. Meanwhile, the British Medical Association called for a "near-elimination" of Covid from the UK before any significant easing of lockdown restrictions.
More than 16 million people in the UK have now had their first does of the vaccine, including 99 per cent of those aged 75 to 79, and more than 93 per cent of those aged 80 and over.
Key studies led by Public Health England involving 40,000 healthcare workers, and 9000 care homes, will be published towards the end of the month. But the Prime Minister is expected to be given early findings, which suggest that both the Pfizer and Oxford/AstraZeneca vaccines have had a powerful effect in stemming the spread of the virus.
A PHE spokesman said: "We have been analysing the data since the start of the vaccination rollout and will publish our findings in due course.
"There is already increasing evidence that the vaccines stop people becoming infected with the disease, cutting hospitalisations and deaths. But the latest data from PHE will show that critically, just one dose of either vaccine appears to block transmission by around two thirds, in all age groups."
The bulk of the latest data being handed to the Government relates to the Pfizer vaccine, which began to be administered in December. But the same effect was seen in a smaller set of findings relating to the Oxford jab, which has been administered far more widely, but started its rollout later.
With either jab, transmission and infections reduced by around two thirds after one dose. Despite concerns about the effectiveness of the Oxford jab in older people, findings were similar in all age groups tracked.
Last week the World Health Organisation recommended the Oxford vaccine for over-65s and backed Britain's decision to administer doses by up to 12 weeks apart, after a number of countries declined to give the jabs to older people. A Whitehall source described the new data as "very encouraging" and in line with findings from clinical trials. Last month a study by Oxford University found a single dose of the AstraZeneca jab cut transmissions by 67 per cent, with no hospitalisation recorded.
Johnson is expected to pore over the data this weekend with advisers Prof Chris Whitty and Sir Patrick Vallance, before a meeting of the Cabinet's coronavirus operations committee.
Covid infection rates are now halving every two weeks, and on current trends, daily cases will fall to 1000 by mid-April. Infection levels have fallen more than two thirds since January, according to the React study, led by Imperial College London.
Yesterday, Baroness Dido Harding, head of NHS Test and Trace, announced job cuts for its call handlers as a result of the declining levels of infection. The latest PHE data found the number of outbreaks in care homes fell from 320 to 181 during the week ending February 11.
It followed the rollout of vaccinations to all eligible care homes for the elderly by the end of last month.
The statistics showed that for people aged 80 and over, the rate of Covid cases fell from 208 per 100,000 to 129.6, a 38 per cent drop. Levels for those in their 70s fell 35.6 per cent, with a drop of 31.2 per cent for those in their 60s.
Meanwhile, two international studies suggested a single dose of the Pfizer vaccine offered protection of at least 85 per cent. Scientists in Israel said this endorsed the UK approach of administering jabs up to 12 weeks. Analysis of documents submitted to the US Food and Drug Administration suggested 92.6 per cent efficacy rates at first dose.
However, a separate study of the Pfizer vaccine found the South African variant may reduce antibody protection by two thirds. The study, published in the New England Journal of Medicine, came less than two weeks after interim data on AstraZeneca's Covid vaccine also raised concern about its efficacy for the same variant. Pfizer scientists have said they are in talks with regulators over a booster engineered for the variant.
Yesterday, Northern Ireland extended its lockdown to April 1, although some primary school pupils would return to classes on March 8.
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