The Scottish researchers analyzed a data set covering the entire Scottish population of 5.4 million, of which 1.1 million — about 20 percent of the population — have received a first dose of the Pfizer or Oxford vaccine. Then they compared the vaccinated against the unvaccinated, and they saw strong evidence of protection.
From December until the middle of February, there were more than 8,000 people who ended up in the hospital for covid-19 in Scotland, but only 58 of those patients came from the vaccinated group.
Combining results for both vaccines for people 80 and older, there was an overall 81 percent reduction in hospital admission by the fourth week, said Aziz Sheikh, professor of primary care research and development at the University of Edinburgh and one of the principal investigators.
Josie Murray of Public Health Scotland, another leader in the study, told science journalists, “The other fantastic news is that we are potentially protecting our NHS hospitals from people needing to attend as a consequence of the covid-19 if they’ve had the vaccine.”
In its initial rollout, the U.K. vaccine campaign prioritized nursing home residents, health workers and all those over 70, who are most at risk of severe illness, hospitalization and death from covid-19. Britain is now asking all those over 65 to roll up their sleeves.
Previous results about vaccine efficacy have come almost exclusively from clinical trials. The first population-level studies have been reported from Israel. They looked at the effectiveness of just one vaccine, Pfizer, which has shown itself 96 percent effective in preventing hospitalizations and death. Israel has vaccinated almost half its adult population.
The Scottish research was released in a preprint Monday and is not yet peer-reviewed. In a statement, the co-developer of the Oxford vaccine, Sarah Gilbert, said the high effectiveness in protecting those over 80 after a single dose increases “confidence in using this vaccine in adults of all ages.”
In second study, also released Monday, Public Health England scientists presented preliminary data that shows the Pfizer vaccine appears to provide high levels of protection not only against symptomatic covid-19 but against infection.
Researchers have been examining a cohort of vaccinated health-care workers every two weeks — whether or not they have covid-19 symptoms — and they found that one dose reduced the risk of infection by more than 70 percent, rising to 85 percent after the second dose.
“This suggests the vaccine may also help to interrupt virus transmission, as you cannot spread the virus if you do not have infection,” the PHE researchers said in a statement.
Alongside these encouraging results, Prime Minister Boris Johnson on Monday outlined the next steps in lifting the country’s third national lockdown, an “exit road map” he said he hoped would be “cautious but also irreversible.”
It will be a slow march, Johnson warned.
He outlined detailed plans in Parliament on Monday, telling lawmakers that there would be four stages, with a minimum of five weeks between each stage.
The earliest possible date that most of the restrictions could be lifted was June 21, the prime minister said.
The first big changes will occur March 8, when all schools in England will reopen; two people from different households will be able to meet outdoors; and nursing home residents in England can receive one regular visitor.
The British government is being far more tentative with easing restrictions this time, even as its vaccination rollout is going astonishingly well — over a quarter of the population has had at least one shot of the vaccine.
The new changes will be rolled out slowly. At each stage, the government says its decisions will be driven by data — figures on the vaccine rollout program, hospital admissions and deaths, infection rates, and impact of any new variants.
The semiautonomous governments in Scotland, Northern Ireland and Wales have their own timetables.