Health Minister Matt Hancock praised the homegrown vaccine as a “game-changer” and said clinical trials have proved the vaccine is safe and effective — but he did not put to rest questions about how effective.
Researchers from the Oxford-AstraZeneca team earlier this month published interim results that showed their vaccine was 62 percent effective for volunteers given two full doses and 90 percent effective for a smaller subgroup who received a half dose followed by a full dose. The scientists said they were studying why the different regimens produced such different results.
Britain’s Medicines and Healthcare products Regulatory Agency authorized the vaccine at two full doses for people 18 and older, concluding the results of the half-dose regimen could not yet be supported.
British regulators also noted data is limited on how well the vaccine works in those over 65, who are among the most vulnerable to the virus but who represented less than 6 percent of the clinical trial participants. But the regulators okayed use in older populations.
Officials said Britain will start inoculating with the AstraZeneca vaccine on Monday, with nursing home residents, health-care workers and people over 80 at the front of the line. There are plans to deliver the vaccine in mass immunization centers, such as sporting arenas and convention halls.
British scientists hailed the authorization as tremendous news and added that this vaccine could help protect not only Britons but many in the developing world. India’s regulatory agency concluded a meeting Wednesday without a decision, but could green light the vaccine next month.
Whereas the United States authorized the Pfizer-BioNTech vaccine just days after Britain, in this case there will be more of a lag.
AstraZeneca is running an additional clinical trial in the United States, with the goal of enrolling 30,000 participants. Moncef Slaoui, the head of the White House Operation Warp Speed, said if the vaccine proves safe and effective, it could be granted emergency authorization in February or March.
The Pfizer-BioNTech vaccine involved a simpler trial design and was shown to be 95 percent effective.
Britain has injected some 600,000 people with the Pfizer vaccine since becoming the first Western country to roll out mass inoculations. But experts say the government must ramp up quickly, to inoculate 2 million people a week — 10 times the current rate — to beat back the pandemic.
The urgency is especially great with a new variant of the virus spreading rapidly. Researchers have found no indication that the variant is deadlier, but it appears to be 50 percent more transmissible.
Britain recorded more than 53,000 cases on Tuesday — the highest in a single day. British hospitals have more coronavirus patients than they did when the first wave gripped the country in April.
As of Thursday, two-thirds of England will be under the highest tier of restrictions. Wales, Scotland and Northern Ireland have enacted tight restrictions, as well.
Hancock said having both the Pfizer and AstraZeneca vaccines means the government now has “a very high degree of confidence that we can be out of this by spring.”
Hancock said that in the interest of injecting as many people as possible, as quickly as possible, it would be sufficient to give a first dose of the AstraZeneca vaccine and allow more than the usual 21 days between shots.
“In the data, the scientists and the regulators have found the immunity comes from around two weeks after the first dose, and then the second dose should be taken up to 12 weeks later to give you that long-term protection,” Hancock said.
“This means we can spend the first three months vaccinating people with the first doses, getting them that immunity, getting people protection quicker than we possibly could have done otherwise,” he said.
Britain bet the house on the AstraZeneca vaccine, ordering 100 million doses, compared to 40 million doses of the Pfizer vaccine and 7 million doses of Moderna, which the United Kingdom did not consider for emergency authorization.
AstraZeneca says it can deliver can deliver two 2 million doses a week, with 40 million doses supplied by the end of March. The company has manufacturing facilities in Britain.
June Raine, chief executive of British regulator, said “no corners were cut” in the rapid review of the new vaccine, even though it was developed at Oxford and backed by the British government. Raine said it has “the potential to save many lives.”
The AstraZeneca vaccine uses a harmless cold virus that typically infects chimpanzees to deliver to the body’s cells the genetic code of the spike protein that dots the outside of the coronavirus. That teaches the body’s immune system to block the real virus.
At a briefing announcing the approval of the vaccine, Wei Shen Lim, a respiratory physician and chairman of the Joint Committee on Vaccination and Immuniztion, said, “The data shared with us, and I am not sure it is entirely in the public domain, calculated the vaccine efficacy between day 22 of dose 1 to the time of dose 2 being given, the figure is around 70 percent.”
Lim added, “but I don’t think I should be revealing any more than that at this point in time.”
In an AstraZeneca news release on Wednesday, the company said “the primary efficacy endpoint based on a pooled analysis showed that the vaccine was 70.4 percent.”
“Today is an important day for millions of people in the U.K. who will get access to this new vaccine,” said Pascal Soriot, chief executive of AstraZeneca. “It has been shown to be effective, well-tolerated, simple to administer and is supplied by AstraZeneca at no profit.”
He said scientists believe the AstraZeneca vaccine will be effective against the new variant detected in Britain.
Public health officials say there is much to recommend the new vaccine, as it costs as little as $3 a dose, is relatively easy to manufacture at huge scale and does not require special handling.
The Pfizer vaccine, which uses a different technology, must be kept in special freezers and dry ice at extremely low temperatures.
The health secretary conceded that the Pfizer requirements “made it more challenging to get out, especially to some of the smaller care homes, and those limitations aren’t there for this Oxford-AstraZeneca vaccine.”
Prime Minister Boris Johnson said the approval of the new vaccine was “truly fantastic news — and a triumph for British science.”
Andrew Pollard, director of the Oxford Vaccine Group, told the BBC that the pandemic this year was “like being in a blizzard.”
“We’ve been really struggling uphill through snow drifts with this icy wind in our faces, and I think this morning we do have some respite with this good news and the warmth that that brings,” he said.