The study, released Monday by scientists at the University of Edinburgh and the University of Strathclyde, examined hospitalization rates among more than 1.1 million Scots who received one shot of either vaccine between Dec. 8 and Feb. 15.
The researchers examined the effectiveness of the vaccines after one week, two weeks, three weeks, four weeks and longer. The highest protection came after four weeks. The Pfizer-BioNTech vaccine lowered the risk of hospitalization by 85 per cent while the Oxford-AstraZeneca jab reduced it by 94 per cent.
“We are over all very, very impressed with both these vaccines. Both are performing incredibly well,” said Aziz Sheikh, professor of primary care research and development at the University of Edinburgh. “We now have national evidence, across an entire country, that vaccination provides protection against COVID-19 hospitalizations.”
Jim McMenamin, a director at Public Health Scotland, said the results were particularly welcomed because they showed effectiveness against the British variant of the virus, which is more contagious and deadlier than the original version. The mutation was first detected in November and now accounts for more than 80 per cent of all cases in Scotland and elsewhere in the U.K. “Certainly for the U.K. variant that we have seen across the time period of the study, this is a very encouraging vaccine effect,” Dr. McMenamin said.
The findings could also ease some fears about the effectiveness of the Oxford-AstraZeneca vaccine in older people.
There have been concerns that the vaccine provides less protection for people over the age of 65 and several countries, including France, Germany and Sweden, have advised that it should only be used in people under that age. There were insufficient data in clinical trials to assess the vaccine’s effectiveness in older age groups, but medical regulators in Britain, the European Union and the World Health Organization have approved its use for all adults.
In Scotland, the Oxford-AstraZeneca vaccine has been used primarily for people over the age of 65 and the study’s findings indicated that it was just as effective in preventing hospitalization. Among the over 80s, the study found an overall 81-per-cent reduction in the numbers admitted to hospital. “From the data that we’ve got at the moment, it seems like this vaccine seems to be working across age groups,” Dr. Sheikh said.
The study did not offer any findings on whether people who have been vaccinated can still pass on the virus. “I think it’s really important to emphasize that these data don’t support any comment about transmission or indeed transmission policy and therefore we wouldn’t be advising on the basis of these results that we should alter anything that we’ve got implemented currently to stop transmission of the virus from person to person within Scotland,” said Josie Murray, a consultant epidemiologist at Public Health Scotland.
There was also no indication as to how long the vaccine protection will last. Both vaccine makers have recommend that people receive a second dose around 28 days after their first shot. However, Britain has delayed the booster shot up to 12 weeks in order to vaccinate more people. The study only looked at efficacy at between 28 and 34 days. The scientists plan to do more research to assess longer-term protection.
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