A single shot of the Pfizer or Oxford vaccine offers dramatic protection against hospital admission and severe disease in older people, according to a new study from Public Health England (PHE).

Health Secretary Matt Hancock hailed the “exciting” real-world data which found either vaccine is more than 80% effective at preventing hospital admission around three to four weeks after the first dose.

England’s deputy chief medical officer Professor Jonathan Van-Tam said the data offered a glimpse of how the vaccine programme “is going to hopefully take us into a very different world in the next few months”.

The study, which has yet to be peer-reviewed, included more than 7.5 million people aged 70 and over in England.

The data also shows that infections (where people display symptoms) in the over-70s fall from around three weeks after one dose of both vaccines.

Protection against even developing symptomatic Covid-19 in the first place ranged between 57 and 61% for one dose of Pfizer and between 60 and 73% for the Oxford/AstraZeneca vaccine, the study found.

On top of the protection against symptomatic disease, people who had been vaccinated with one dose of Pfizer had an additional 43% lower risk of emergency hospital admission and an additional 51% lower risk of death, according to the study.

Meanwhile, people who had been vaccinated with one dose of the Oxford vaccine had an additional 37% lower risk of emergency hospital admission, while there is currently insufficient follow-up data to assess the impact on death.

The authors said that “both vaccines show similar effects”, adding: “Combined with the effect against symptomatic disease, this indicates that a single dose of either vaccine is approximately 80% effective at preventing hospitalisation and a single dose of (Pfizer) is 85% effective at preventing death with Covid-19.”

Mr Hancock told a Downing Street press conference the study was “extremely good news”.

He added: “In fact, the detailed data show that the protection that you get from catching Covid 35 days after a first jab is even slightly better for the Oxford jab than for Pfizer, albeit both results are clearly very strong.”

The results “may also help to explain why the number of Covid admissions to intensive care units among people over 80 in the UK have dropped to single figures in the last couple of weeks”.

Prof Van-Tam told the briefing the data “gives us those first glimpses of how, if we are patient, and we give this vaccine programme time to have its full effect, it is going to hopefully take us into a very different world in the next few months”.

Urging people to have their second doses, he added: “I think there’s quite a significant likelihood that a second dose of vaccine is going to mature your immune response, possibly make it broader and almost certainly make it longer than it would otherwise be in relation to a first dose only.”

That meant it was “absolutely critical” that second doses “are still part of the course of immunisation against Covid-19 and no less important for that reason”.

Prof Van-Tam said the latest scientific data had “vindicated” the UK’s decision to give the AstraZeneca vaccine to older people.

Some countries have refused to administer the vaccine to the over-65s because of a lack of clinical trial data on older age groups.

However, Prof Van-Tam said the Joint Committee on Vaccination and Immunisation had taken the view that it was “not immunologically plausible” the vaccine would work in younger age groups but not older ones.

He added: “We took a view that it almost certainly would work. The PHE (Public Health England) data have clearly vindicated that approach today.

“I am not here to criticise other countries but to say that I think in time the data emerging from our programme will speak for itself and other countries will doubtless be very interested in it.”

Dr Mary Ramsay, PHE head of immunisation, said of the study: “This adds to growing evidence showing that the vaccines are working to reduce infections and save lives.

“While there remains much more data to follow, this is encouraging and we are increasingly confident that vaccines are making a real difference.

“It is important to remember that protection is not complete and we don’t yet know how much these vaccines will reduce the risk of you passing Covid-19 on to others.

“Even if you have been vaccinated, it is really important that you continue to act like you have the virus, practise good hand hygiene and stay at home.”

The study was carried out with Public Health Wales, Public Health Agency Northern Ireland and Health Protection Scotland.

There was also input from the University of Strathclyde, the NIHR Health Protection Research Unit in Vaccines and Immunisation at the London School of Hygiene and Tropical Medicine and the NIHR Health Protection Research Unit in Respiratory Infections at Imperial College London.