The Oxford AstraZeneca vaccine could reduce coronavirus transmission by as much as two-thirds, a study suggests, showing for the first time that a shot has such an effect.
The University of Oxford study released Tuesday, which is pending peer review, found that those vaccinated with a single dose of the vaccine were 67 percent less likely to test positive with a PCR test.
The paper suggested that the vaccine, developed by Oxford University in collaboration with the British-Swedish pharmaceutical giant AstraZeneca, could have a “substantial effect on the transmission of the virus” as a result and also prevent serious illness.
Health Secretary Matt Hancock said the study, which also suggested that the Oxford-AstraZeneca injection is highly protective after a single dose, showed that “vaccines are the way out of this pandemic.”
“This news about the Oxford vaccine is absolutely fantastic,” Hancock tweeted. “This vaccine works and works well.”
This news about the Oxford vaccine is absolutely fantastic.
📉 2/3 reduction in transmission
Stronger protection from a 12-week period between doses
🏥 No hospital admissionsThis vaccine works and works well 🇬🇧
https://t.co/B1WPLf6dJB– Matt Hancock (@MattHancock) February 2, 2021
Oxford academics approve a 12-week dose interval
The study also found that after a single dose, the vaccine was 76 percent effective against symptomatic infection for three months, a level that increased if the second injection was delayed.
The results of studies in Great Britain, Brazil and South Africa showed that immune responses were enhanced with a longer interval between the two doses, in participants 18 to 55 years old.
“The vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 post-vaccination was 76 percent, and modeled analysis indicated that protection did not decrease during this initial 3-month period,” Oxford academics said.
Their paper added that the vaccine’s efficacy was 82.4 percent by 12 or more weeks until the second dose, compared to 54.9 percent for those with the booster given less than six weeks after the first dose.
The findings supported the UK’s decision to extend the interval between the initial and booster dose of the shots to 12 weeks, Oxford academics said.
The UK has decided to vaccinate as many people as possible as soon as possible by increasing the time between the first injections and the booster shots.
Andrew Pollard, principal investigator of the Oxford Vaccine Trial, said the data shows that the 12-week interval was “the optimal approach to deploy, assuring us that people are protected from 22 days after a single dose.”
AstraZeneca’s head of study has said eight to 12 weeks between doses seemed to be the “sweet spot” for efficacy, unlike Pfizer, who warned that its vaccine – developed with Germany’s BioNTech, has not been tested at such an interval. .
Questions about the elderly
The study did not address growing questions about a lack of data on efficacy in the elderly, a group that the UK government has given top priority in the introduction of vaccines.
The longest interval between doses for subjects 56 years of age and older was between six and eight weeks, so there were no data on the efficacy of a 12-week dosing gap in that cohort.
The study said that none of the 12,408 people vaccinated with a single dose of the vaccine had been hospitalized with COVID-19 from 22 days after immunization.
The European drug regulator has recommended the Oxford AstraZeneca vaccine for adults of all ages, but also indicated that there is not enough data to determine how well it will work in people over 55 years old.
On Tuesday, Poland and Sweden joined countries that have decided not to use AstraZeneca in the elderly.
The UK has expressed confidence that the vaccine will work in all age groups and is ahead of other EU countries in the pace of vaccine introduction as vaccines have been approved earlier.
Oxford University’s Pollard said Wednesday that the team’s researchers also believe the vaccine will continue to provide protection against new variants of COVID-19, although they are still waiting for data on this.
Even if the virus does adapt, “that doesn’t mean we still won’t have protection against serious illness,” he said.
“If we have to update the vaccines, it is actually a relatively simple process that only takes a matter of months, rather than the huge efforts that everyone put into the very large-scale trials last year,” Pollard said. the BBC.