A single dose of the AstraZeneca
COVID-19 vaccine offers 76% protection for up to three months after the first injection and appears to reduce transmission, according to new research by the University of Oxford.
Preliminary results of the study, published in medical journal The Lancet on Wednesday but not yet peer-reviewed, seemingly support the U.K. government’s policy of choosing to delay second doses of vaccines in order to inoculate as many people as quickly as possible. The study suggests that the government’s 12-week gap between doses doesn’t lower protection.
The researchers found that vaccine efficacy was 76% after a first dose, with that protection maintained to the second dose. The shot’s effectiveness in preventing coronavirus disease rises to 82.4% once a second dose is administered after 12 weeks.
The findings also showed a 67% reduction in positive COVID-19 swabs among those vaccinated, suggesting the AstraZeneca
vaccine — which the U.K.-Swedish drug company developed with the University of Oxford — has a “substantial impact” on reducing transmission of the virus that causes the disease. But the researchers cautioned that a much bigger sample will be needed to reach definitive conclusions on transmission risk.
“These new data provide an important verification of the interim data that has helped regulators to grant the vaccine emergency use authorization.”
Prof. Andrew Pollard, chief investigator of the Oxford Vaccine Trial, and co-author of the paper, said the new data provide an “important verification” of the interim data” that has helped regulators in the U.K. and elsewhere grant the vaccine emergency-use authorization.
“It also helps to support the policy recommendation made by the Joint Committee on Vaccination and Immunisation for a 12-week prime-boost interval, as they look for the optimal approach to roll out, and reassures us that people are protected 22 days after a single dose of the vaccine,” Pollard added.
The data was based on 17,177 participants in trials in the U.K., Brazil and South Africa.
The findings were welcomed by health secretary Matt Hancock, who said on Twitter
that the results were “absolutely superb” and showed “vaccines are the way out of this pandemic.”
More than 9.7 million people in the U.K. have already received their first dose of a vaccine, according to the latest government figures.
Shares in AstraZeneca inched 0.61% higher in early London trading on Wednesday.
“New data showing the AstraZeneca COVID vaccine to be highly effective with a 12-week gap between doses has put a spring in the step of markets. It revives a sense of optimism towards society reopening sooner rather later,” said Russ Mould, investment director at AJ Bell.
The study comes after public health agencies in Belgium, France, Sweden, Poland and Austria imposed age limits on who should receive the AstraZeneca–Oxford vaccine, over concerns that it may not be effective in those aged over 65 years.
French President Emmanuel Macron referred to the AstraZeneca vaccine as “quasi-ineffective” on people aged over 65, as the country joined Sweden and Belgium in saying it wouldn’t administer the shot to anyone over the age of 64, while Poland set its threshold at 60 years.
Last week, Germany’s vaccine committee was the first European Union member state to recommend the AstraZeneca–Oxford shot only be used on those between 18 and 64 years of age, citing “insufficient data.”
Italy’s medicines regulator AIFA advised those aged over 55 to instead be inoculated with the vaccine developed by U.S. drug company Pfizer
and its German partner BioNTech
or the one developed by U.S. biotech Moderna
which use the messenger RNA approach. This instructs cells to create proteins to generate an immune response protecting against a virus.
The European Medicines Authority, which last week gave the AstraZeneca–Oxford vaccine the green light to be used in the 27-member bloc, acknowledged that most of the participants in the AstraZeneca vaccine trials were between 18 and 55 years old, and that there weren’t enough results in older people to provide a figure for how well it will work in this group.