By Joseph Walker and Jenny Strasburg
LONDON -- The U.K. authorized a Covid-19 vaccine developed by
the University of Oxford and AstraZeneca PLC, opening the door for
distributing millions of doses in a country where a more infectious
variant of the coronavirus has contributed to surging cases.
British health officials also recommended a delay of up to three
months between both doses of the vaccine, guidance that also
applies to the shot developed by Pfizer Inc. and BioNTech SE that
the U.K. authorized earlier this month. The delay will allow
inoculations to reach more people more quickly as the variant
pushes new cases to records and hospitalizations soar.
The green light represents the third emergency-use approval of a
Western-developed vaccine this month and comes as cases rise
sharply in Europe and the U.S., which reported its first confirmed
case of the variant Tuesday. The Pfizer-BioNTech shot and one
developed by Moderna Inc. have been cleared in the U.S.
The Oxford-AstraZeneca vaccine stands out on price, convenience
and global ambition. AstraZeneca has promised to make as many as
three billion doses available in 2021 -- more than any other
Covid-19 vaccine maker -- and at a cheaper price. The U.K. company
says it won't profit from the shot during the pandemic, or ever in
the case of poorer countries. The vaccine also can be transported
and stored for months with normal refrigeration, making it easier
to distribute where people and health-care networks are sparse or
underfunded. The two other Western vaccines in use require
ultracold temperatures for all but a few days or weeks.
AstraZeneca's shot -- less effective in clinical trials than its
rivals' injections -- won't be available in the U.S. until the Food
and Drug Administration reviews large-scale trials still being
conducted there and decides whether to authorize its use.
The mutated virus recently led some nations to ban visitors and
goods from Britain, increasing the political urgency for a speedy
vaccine rollout here. The government has said that more than
600,000 doses of the Pfizer-BioNTech vaccine have been
administered.
Scientists have said that the three Covid-19 vaccines authorized
by Western countries so far should be similarly effective against
the new variant as they have been in clinical trials, a view
AstraZeneca executives share, according to a person familiar with
the matter. The variant could be as much as 70% more transmissible
than more established forms of Covid-19, government officials
say.
The U.K. medicines regulator said the vaccine can be
administered to people 18 years and older. The authorization clears
the use of two standard vaccine doses, a regimen that was 62%
effective in preventing symptomatic Covid-19 in an interim analysis
of trials involving about 11,600 people in the U.K. and Brazil.
In the same study, a small subset of volunteers of ages 55 and
younger were given a half-dose shot followed by a standard dose.
That subset showed a higher protection rate of 90%. The U.K.
government hasn't authorized the use of the half-dose regimen.
"We felt the results were not borne out by the full analysis,"
Munir Pirmohamed, a pharmacologist who chairs the government's
advisory group that advised on the regulator's recommendations,
said Wednesday.
U.K. officials said they authorized the vaccine Tuesday and
released the first batches that night.
They advised that no preference generally should be given
between the two vaccines so far authorized by the U.K. The higher
efficacy shown by the Pfizer vaccine isn't directly comparable with
that of the Oxford-AstraZeneca shot, officials said, because of
scientific and clinical-trial differences.
AstraZeneca and U.K. health officials said the two-dose regimen
is flexible in terms of when the second dose should be given,
anywhere from four weeks to 12 weeks after the first.
Delaying the second dose would help stretch supplies so more
Britons get a first shot sooner. But the vaccine's full protection
-- benefits shown in clinical trials to prevent hospitalization --
kicks in only after the second dose.
U.K. health officials said Wednesday the updated second-dose
guidance also applies to the Pfizer-BioNTech shot already being
administered in the country. Previously, the second dose was
recommended 21 days after the first. U.K. officials changed that
Wednesday to "within 12 weeks," citing the latest scientific
advice. The vaccine's makers have said full protection doesn't
start until at least seven days after the second dose.
Pfizer has promised the U.K. millions more doses by the end of
the year, but the AstraZeneca and Oxford shot -- made at facilities
in the country and elsewhere -- promises to accelerate inoculations
by the country's state-run health-care system. The National Health
Service will determine which shot to provide people depending on
supply.
AstraZeneca said Wednesday it would supply millions of doses in
the first quarter of next year, without specifying an exact number.
The U.K. has ordered up to 100 million doses, enough for 50 million
people.
Government advisers behind the authorization said the 90%
efficacy shown in the half-dose regimen might have been caused by
the longer period between the first and second doses in that trial
subgroup, rather than by the half-dose itself. They said the
analysis of the half-dose subgroup contributed to authorities'
decision to recommend up to 12 weeks between doses.
The advisers said for the full-dose regimen, immunity kicks in
roughly three weeks after the first dose. They estimated 70%
effectiveness in the vaccine during the period from three weeks
after the first dose through the next three months. They said it
isn't clear whether that number will hold up in fuller clinical
trials.
It is unclear how quickly other nations might authorize the
vaccine. A large clinical trial is under way in the U.S., where
AstraZeneca executives expect to have full trial data to submit by
February, according to a person familiar with the matter. They have
been submitting batches of data to European regulators and are
poised for potential authorization across the European Union by
February, the person said.
AstraZeneca's U.S. study has so far enrolled 29,700 volunteers
out of a planned 30,000 volunteers, and an emergency-use
authorization could be granted in early April if the study results
are positive, Moncef Slaoui, chief adviser to the federal Operation
Warp Speed initiative, told reporters Wednesday. If the vaccine is
authorized that month, the U.S. government expects several tens of
millions of doses to be available for distribution, he said.
Dr. Slaoui said he has no doubt that the vaccine is effective in
preventing severe disease in the population where it has been
tested. However, he said, "For me, the biggest question mark,
frankly, is efficacy in the elderly population that needs to be
further documented" because the U.K. and Brazilian studies didn't
enroll enough older volunteers early in the trials.
Oxford and AstraZeneca emerged early this year as front-runners
in the race to develop a Covid-19 vaccine before falling behind
competitors that completed clinical trials faster. Developed by
scientists at Oxford's Jenner Institute, the vaccine uses a
weakened cold virus to courier genetic material from the
coronavirus into cells and trigger immunity.
AstraZeneca agreed in April to co-develop Oxford's technology
and distribute it around the world at no profit during the
pandemic. By November, the company had agreements to supply three
billion doses to every region in the world.
The partners have faced setbacks along the way to Wednesday's
milestone. In May, they launched a combined Phase 2 and 3 clinical
trial in the U.K. aimed at enrolling more than 10,000 volunteers
and obtaining initial results by August. But the study progressed
slower than initially hoped, partly because of relatively low
infection rates in the U.K. for much of the summer and fall.
By the time AstraZeneca launched a planned Phase 3 U.S. study of
30,000 volunteers in late August, the company was trailing Pfizer
and Moderna, which had begun similarly sized studies a month
earlier. Within two weeks, AstraZeneca paused all its studies
globally after a U.K. volunteer had an unexplained illness. U.K.
regulators allowed studies to resume quickly, but the U.S. trial
remained grounded for more than six weeks before U.S. regulators
lifted the hold in October.
Write to Joseph Walker at joseph.walker@wsj.com and Jenny
Strasburg at jenny.strasburg@wsj.com
(END) Dow Jones Newswires
December 30, 2020 16:12 ET (21:12 GMT)
Copyright (c) 2020 Dow Jones & Company, Inc.
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