LONDON – Britain became the first country on Wednesday to give emergency clearance for the coronavirus vaccine developed by AstraZeneca and the University of Oxford, paving the way for a cheap and easy-to-store injection with which large part of the world will count to help end the pandemic.
In a bold decision to speed up vaccinations, a British government advisory body instructed doctors to administer as many people as possible their first dose of a coronavirus vaccine, without reserving supplies for the second planned doses.
Instead of administering the two injections in one month, doctors will wait up to 12 weeks to give people their second doses, the government said, a decision that applies to the Oxford-AstraZeneca vaccine, as well as the Pfizer-BioNTech vaccine authorized by Britain Britain earlier this month.
With the implementation of vaccination progressing slowly in Britain and the United States, British authorities were responding to calls to delay second doses as a way to give more people partial protection from a single dose. Matt Hancock, the health secretary, said people would start receiving the AstraZeneca vaccine early next week.
For Britain, where hospitals are overwhelmed by a barrage of cases of a new, more contagious variant of the virus, the decision of its drug regulator offered some hope of suspension. The health service is preparing to vaccinate a million people a week soon in makeshift places in football stadiums and racetracks.
The Oxford-AstraZeneca injection is about to become the dominant form of inoculation in the world. Costing $ 3 to $ 4 a dose, it is a fraction of the cost of some other vaccines. And it can be shipped and stored at normal refrigerated temperatures for six months, instead of in the ultracold freezers required by rival vaccines from Pfizer-BioNTech and Moderna, making it easier to administer to people in the poorest and most difficult parts of the world.
When given in two full strength doses, the AstraZeneca vaccine showed 62 percent effectiveness in clinical trials – considerably lower than the approximately 95 percent effectiveness achieved by injections from Pfizer and Moderna. For reasons that scientists still don’t understand, the AstraZeneca vaccine has shown 90 percent effectiveness in a smaller group of volunteers who received an initial half-dose.
In announcing the authorization on Wednesday, the UK Department of Health did not immediately outline which dosing regimen was authorized, or whether doctors would be free to choose between the two.
In addition to dosing issues, Britain’s health service must also find out how to persuade people to get a vaccine that seems less effective than the other vaccines available, but which, however, can hasten the end of a pandemic that it has killed hundreds of people every day in Britain and thousands more worldwide.
The authorization was based on data from advanced clinical trials in Great Britain and Brazil. The Indian drug regulator is also due to decide soon whether to authorize the vaccine, which is being manufactured by a local vaccine producer, the Serum Institute.
A decision is still far in the United States, where the Food and Drug Administration is awaiting data from a separate clinical trial. The study was halted in September and delayed for nearly seven weeks – much longer than in other countries – as regulators investigated whether a disease in a UK participant was related to the vaccine. American regulators finally allowed the trial to continue.
In the past few days, Oxford scientists who developed the vaccine have entered into a debate on both sides of the Atlantic over whether to delay the planned second doses of this and other vaccines as a way to give more people partial protection from a single dose. Andrew Pollard, director of the Oxford Vaccine Group, said in a radio interview on Monday that “it makes a lot of sense to start with as many people as possible”, postponing the second dose.
AstraZeneca has set more ambitious manufacturing goals than other vaccine manufacturers, saying it expects to be able to produce up to three billion doses in the next year. With two doses per person, this would be enough to inoculate almost one in five people worldwide. The company has pledged to make it available at cost throughout the world until at least July 2021 and in the poorest countries perpetually.
But the company has also been affected by communication errors that have damaged its relationship with American regulators and raised doubts about whether the vaccine will withstand intense public and scientific scrutiny. These errors disrupted the vaccine schedule in the United States, where top FDA officials were surprised to learn of the pause in their clinical trials in September, not by AstraZeneca, but by the media.
These setbacks have not dampened enthusiasm in Britain for the country’s leading national vaccine, which, analysts say, could correct the course of Prime Minister Boris Johnson’s mandate if implemented quickly.
Having ordered 100 million doses, 40 million of which should be available by March, Britain has made the AstraZeneca injection the cornerstone of its vaccination strategy. Since Pfizer’s vaccine was authorized 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 doctors’ offices, leaving some of its highest priority beneficiaries, as nursing home residents, still vulnerable.
A small number of volunteers in the clinical trial in Britain received their first dose at half the dose due to a measurement problem. Oxford hired an outside manufacturer to produce the vaccine for the test. But when the researchers received a sample of the vaccine, they found that its strength was twice that of what the manufacturer had found using a different measurement technique. Without knowing how much to trust, the researchers decided to cut the dose in half to ensure that the volunteers did not receive twice the dose originally planned. Later, Oxford researchers confirmed that their reading was too high and they went back to the dose originally planned for the second injection.
In the smaller group of 2,741 people who received the first dose at half strength or a meningococcal vaccine as a control, the vaccine was 90 percent effective. None of these participants were older than 55, however, making it difficult to know whether these results would hold on to older people.
Scientists at AstraZeneca and Oxford said they do not know why the initial half-dose was so much more effective. But they expressed confidence in their results, especially the discovery that no one who received the vaccine in clinical trials developed severe Covid-19 or was hospitalized.
“We think we have found the winning formula and how to achieve effectiveness that, after two doses, is up to everyone else,” Pascal Soriot, chief executive of AstraZeneca, told The Times of London in an interview published on Saturday. The company has not released evidence of efficacy rates as high as those of Pfizer or Moderna. “I can’t say any more because we will publish at some point,” Soriot told The Times.
Oxford scientists earlier this month published provisional findings from clinical trials of the vaccine in The Lancet. The next final results of these trials are not expected to be significantly different from the provisional data, as is typical in clinical research.
The AstraZeneca test in the United States had enrolled more than 27,000 participants last week, just below its target of 30,000. The trial could have results and, if positive, lead to an emergency clearance in the United States in February or March, Moncef Slaoui, head of Operation Warp Speed, told the US federal effort to accelerate coronavirus vaccines. Last week.
AstraZeneca executives publicly presented several ideas for collecting additional data on the most promising dosing regimen. In November, they said they were considering adding an arm to the ongoing US trial or starting a new global test. But so far, none of these proposals have materialized.