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LONDON – Britain on Wednesday became the first country to grant emergency clearance to the coronavirus vaccine developed by AstraZeneca and the University of Oxford, clearing the way for a cheap and easy-to-store injection in which much of the world it will depend to help end the pandemic.
In a bold departure from prevailing strategies around the world, the British government also decided to start giving as many people as possible a first dose of coronavirus vaccines, rather than withholding supplies for second rapid injections, greatly expanding Measure the amount of people that will be inoculated.
That decision put Britain at the forefront of an uncertain and far-reaching experiment to speed up vaccines, one that some scientists believe will reduce the suffering caused by a pandemic that has killed hundreds of people every day in Britain and thousands more. all over the world. .
The effects of delaying second doses as a way to give more people the partial protection of a single dose are not fully understood. Britain, considered by experts to be the first country to undertake such a scheme, will also delay second doses of the Pfizer-BioNTech vaccine, which has been in use there for several weeks and has been shown in clinical trials to be effective. considerable after a single dose.
Some participants in the Oxford-AstraZeneca vaccine clinical trial received the two doses several months apart. British regulators said on Wednesday that the first dose of the vaccine was 70 percent effective in protecting against Covid-19 in the period between the effect of the injection and the administration of a second, although those figures held for a Limited subset of trial participants and have not been published.
Together, Britain’s two moves – authorizing the Oxford-AstraZeneca vaccine and lengthening the dose gap – offered the clearest signal yet of how countries still low on the virus could accelerate the pace of vaccination programs.
Oxford-AstraZeneca injection is poised to become the world’s dominant form of inoculation. At $ 3 to $ 4 a dose, it is a fraction of the cost of some other vaccines. It can also be shipped and stored in normal refrigerators for six months, rather than in the ultra-cold freezers that require Pfizer-BioNTech and Moderna vaccines, making it easy to administer to people in the poorest and hard-to-reach parts of the world .
“This is very good news for the world, it makes a global approach to a global pandemic much easier,” said Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine. On the decision to delay second doses, he said: “In a pandemic, it will be better to provide more people with some level of protection than for everyone who gets vaccinated to get full protection.”
Instead of giving the two injections of the coronavirus vaccines within a month as originally planned, doctors in Britain will wait up to 12 weeks to give people a second dose, the government said. Matt Hancock, the health secretary, said people would start getting the AstraZeneca vaccine early next week.
For Britain, where hospitals are overwhelmed by a flood of cases of a new, more contagious variant of the virus, its drug regulator’s decision offered some hope of relief. The health service is preparing to soon vaccinate a million people a week in makeshift locations in football stadiums and racetracks.
When given in two full doses, AstraZeneca’s vaccine showed 62 percent efficacy in clinical trials, considerably lower than the approximately 95 percent efficacy achieved by Pfizer and Moderna injections. For reasons not yet understood by scientists, AstraZeneca’s vaccine showed 90 percent efficacy in a smaller group of volunteers who received a half-potency starting dose.
British regulators licensed the vaccine in two full doses, saying the more promising results from the other regimen were not confirmed by a full analysis. They cautioned that the promising efficacy results after a single dose of the vaccine were sustained in only a limited number of trial participants.
In recent days, the Oxford scientists who developed the vaccine have expressed some support for delaying second doses. Andrew Pollard, director of the Oxford Vaccine Group, said in a radio interview Monday that it made “a lot of sense to start with as many people as possible” by delaying the second dose.
The British health service must now find a way to persuade people to get a vaccine that seems less effective than other available vaccines, but could nonetheless hasten the end of the pandemic.
The authorization was based on data from late-stage clinical trials in Great Britain and Brazil. India’s drug regulator is also expected to decide soon whether to authorize the vaccine, which is being manufactured there by a local vaccine producer, the Serum Institute.
The decision is further afield in the United States, where the Food and Drug Administration is awaiting data from a separate clinical trial. The study was stopped in September and delayed for nearly seven weeks, much longer than in other countries, while regulators investigated whether an illness in a participant in Britain was related to the vaccine. US regulators finally allowed the trial to continue.
AstraZeneca has set more ambitious manufacturing targets than other vaccine manufacturers, and says it expects to be able to produce up to three billion doses next year. At two doses per person, that would be enough to inoculate nearly one in five people worldwide. The company has committed to making it available at cost worldwide until at least July 2021 and in the poorest countries in perpetuity.
But the company has also been plagued by communication errors that have damaged its relationship with US regulators and raised questions about whether the vaccine will withstand intense public and scientific scrutiny. Those mistakes have pushed back the vaccine schedule in the United States, where key FDA officials were surprised to learn of the pause in their clinical trials in September not from AstraZeneca, but from the media.
These setbacks have not dampened enthusiasm in Britain for the country’s main homegrown vaccine, one that analysts have said could correct the course of Prime Minister Boris Johnson’s term if quickly implemented.
After ordering 100 million doses, 40 million of which are expected to be available by March, Britain has made the AstraZeneca injection the centerpiece of its vaccination strategy. Since authorizing the Pfizer vaccine on December 2, Britain has used it to vaccinate hundreds of thousands of people. But the country has struggled to manage it beyond hospitals and doctor’s offices, leaving some of its highest-priority audiences, such as nursing home residents, still vulnerable.
“We believe that we have discovered the winning formula and how to achieve an efficacy that, after two doses, is on par with all the others,” Pascal Soriot, CEO of AstraZeneca, told The Times of London in an interview published on Saturday. . The company has not published evidence of efficacy rates as high as those of Pfizer or Moderna. “I can’t tell you more because we will publish at some point,” Soriot told The Times.
Oxford scientists published interim findings from clinical trials of the vaccine in The Lancet this month. The next final results from these trials are not expected to be significantly different from interim data, as is typical in clinical research.
The AstraZeneca trial in the US had enrolled more than 27,000 participants as of last week, just shy of its goal of 30,000. The trial could have results and, if positive, lead to an emergency clearance in the United States in February or March, said Moncef Slaoui, head of Operation Warp Speed, the United States’ federal effort to speed up coronavirus vaccines. at a press conference. last week.
