The Pfizer and AstraZeneca vaccines are more than 80% effective at preventing hospitalisations from Covid-19 in those over 80 after one dose of either shot, Public Health England (PHE) said on Monday, citing a pre-print study.

PHE said the real world study, with data generated from Britain’s vaccine rollout, also found that protection against symptomatic Covid in those over 70 ranged between 57-61% for one dose of Pfizer-BioNTech’s vaccine and between 60-73% for the Oxford-AstraZeneca one four weeks after the first shot.

“These 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, which is something I know that we all welcome,” health minister Matt Hancock said at a news conference.

“This is seriously encouraging.”

PHE added that evidence for the Pfizer vaccine suggested it leads to an 83% reduction in deaths from Covid-19. There was not equivalent data on mortality effect of the AstraZeneca vaccine, which began to be administered at a later date.

PHE Head of Immunisations Mary Ramsay said that while more work needed to be done to understand the impact on vaccines in reducing transmission of the coronavirus, the effect of the rollout was already apparent.

“This adds to growing evidence showing that the vaccines are working to reduce infections and save lives,” she said.

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

Another PHE official said that more work needed to be done to establish the efficacy of vaccines against the so-called Brazilian variant of the coronavirus.