LONDON – The first population-level real-world data on COVID-19 vaccines indicate they are having a dramatic impact on severe disease, with a study in Scotland showing a fall of 85% in hospital admissions for people who received the Pfizer Inc./Biontech SE product, and a drop of 94% for those who had Astrazeneca plc’s vaccine, four weeks after receiving the first dose.

The findings are based on 5.4 million people in Scotland, following administration of 1.14 million first doses of vaccine between Dec. 8, 2020, and Feb. 15, 2021. Importantly, they show there was an overall reduction of 81% in the most vulnerable group – of people over age 80 – being admitted to the hospital in that time.

The study of just over 8,000 patients who were admitted to the hospital with COVID-19, shows the vast majority had not been vaccinated. Only 58 of hospitalized cases were in people who had received a single dose of one of the two vaccines.

The researchers had access to individual National Health Service numbers, allowing them to track in near real time general practitioner records on vaccination, laboratory test results, hospital admissions and deaths. They analyzed the data every week to compare outcomes for those who had their first vaccine dose and those who had not.

The study team said the findings are applicable to other countries rolling out Pfizer/Biontech and Astrazeneca vaccines. Although it appears Astrazeneca may be more effective in preventing hospitalization of in people over 80, the data do not allow for comparisons between the two products.

Rollout in Scotland began with the Pfizer/Biontech vaccine initially being administered to health care workers and in people older than 80. By the time of the data cut-off, 650,000 people had received the Pfizer/Biontech vaccine and 490,000 had received the Astrazeneca vaccine.

“We now have national evidence across an entire country that vaccination provides protection against COVID-19 hospitalization,” said Aziz Sheikh, lead researcher on the study, who is director of Edinburgh University’s institute of Molecular, Genetic and Population Health Science.

The findings are a significant corroboration of the U.K.’s controversial strategy of attempting to maximize the public health benefits of limited vaccine supplies by administering as many first doses as possible. Rather than three or four weeks between doses as instructed on the labels, the second dose is being given 12 weeks after the first.

Based on the data from Scotland, “Rollout of the first vaccine dose now needs to be accelerated globally,” Sheikh said.

The study also is important in demonstrating a positive effect of the Astrazeneca vaccine in older people, because data for that group was not available from the phase III trials.

Although EMA approval is for everyone age 18 and older, the lack of information on how the vaccine performed in older people led some countries in Europe, notably Germany, to say Astrazeneca’s vaccine should only be given to those under 65.

“It’s clear [the] Astrazeneca [vaccine] does work in older people,” said the U.K. government chief scientist Patrick Vallance, commenting on the results.

Reducing asymptomatic infections, too

Further welcome news is that more than 80% of cases of SARS-CoV-2 infection now being diagnosed by PCR test in Scotland involve the more transmissible B.1.1.7 variant that was first detected in southeast England in December. That shows the vaccines are effective against this variant, the researchers said.

This was confirmed in the first data on the impact of Pfizer/Biontech’s vaccine in England, released just after the results of the Scottish study.

Public Health England (PHE) published analyses from two separate studies, with the first, in 40,000 health care workers, indicating one dose reduces the risk of being infected with SARS-CoV-2 by 70%, rising to 85% after the second dose.

The health care workers in the study have a PCR test for COVID-19 every two weeks, whether or not they have symptoms, so that suggests the Pfizer/Biontech vaccine may also help to interrupt virus transmission.

“Overall, we are seeing a really strong effect in reducing infections, including asymptomatic [ones],” said Susan Hopkins, strategic response director at PHE. In the Pfizer/Biontech phase III studies, participants were only tested if they had COVID-19 symptoms, making the PHE analysis the first to have demonstrated the vaccine reduces asymptomatic infections, Hopkins noted.

PHE also released an analysis based on community testing, which shows one dose of Pfizer/Biontech’s vaccine is 57% effective in preventing symptomatic COVID-19 in people over 80 years of age, three to four weeks after the first dose. Early data imply that rises to more than 85% following the second dose.

For those who do contract COVID-19, the risk of dying for those over 80 is 56% less in vaccinated cases compared to unvaccinated cases, by 14 days after receiving the first dose.

“The key thing is the link to hospitalizations and death. Even if you do get COVID, the risk of hospitalization is 40% lower, and the risk of death 57% lower, if you are vaccinated,” said Mary Ramsay, head of immunization at PHE. It is expected the size of that effect will increase over time.

The U.K. currently is under strict control measures, with schools, colleges, non-essential shops and the hospitality sector all closed. That makes it hard to separate out the impact of lockdown from that of vaccines.

However, both the Scottish and English data show that while hospitalization and death rates are falling in all groups, the oldest age groups are seeing the fastest decline, since the peak of infection in mid-January. That was not the case in the first lockdown in March last year, when the number of infections in older people fell more slowly than in the population as whole.

“Most of the decline [this time] is probably due to lockdown. But the faster decline is down to vaccination,” Ramsay said.

PHE said it will publish data on the real world impact of the Astrazeneca vaccine soon, but early signals suggest it, too, is providing good levels of protection from the first dose.

“These are pretty impressive vaccines, working in the most challenging people. The second dose will provide more protection, and we are hopeful of protection against variants,” said Ramsay.