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
the rollout of millions of doses in a country where infections have
surged amid a more infectious variant of the virus.
The green light represents the third emergency-use approval of a
Western-developed vaccine this month and comes as cases rise
sharply in the U.S. and Europe. A shot developed by Pfizer Inc. and
Germany's BioNTech SE and one by Moderna Inc. have both been
cleared in the U.S. and are being distributed there.
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 to authorize its use.
The U.K. authorization comes as the country battles a new,
potentially more contagious variant of the coronavirus. The mutated
virus triggered travel bans recently on visitors and goods from
Britain, ratcheting up the political urgency for a speedy vaccine
rollout here. Pfizer's shot is already available in the U.K., where
Prime Minister Boris Johnson said on Dec. 21 that a half million of
the first of a two-dose regimen 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 new variant could be as much as 70% more
transmissible than more established forms of Covid-19, government
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 age 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 in a media briefing 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
Oxford-AstraZeneca vaccine and the Pfizer-BioNTech vaccine. The
higher efficacy shown by the Pfizer vaccine isn't directly
comparable with the efficacy of the Oxford-AstraZeneca vaccine,
officials said, because of scientific and clinical-trial
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 dose.
Delaying the second dose would help stretch supplies of the
vaccine so more Britons get a first shot sooner. But the vaccine's
full protection -- benefits shown in clinical trials to prevent
hospitalization -- only kicks in 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 second dose. U.K. officials on
Wednesday changed that to "within 12 weeks," saying the change was
based on 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 quicken the rate of
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 will 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 of the vaccine, enough
for 50 million people.
The vaccine provided between 62% and 90% effectiveness against
symptomatic Covid-19, depending on dosage size. Two full doses
about a month apart led to the 62% reading, while a small subset of
trial volunteers who received a lower initial dose followed by a
second standard dose showed a 90% efficacy reading. That subset of
trial participants were all 55 or younger. Oxford and AstraZeneca
scientists have said they are unsure why that regimen would be more
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 to
U.S. regulators 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.
Oxford and AstraZeneca emerged early this year as front-runners
in the race to develop a Covid-19 vaccine before falling behind
competitors that were able to complete 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 with two shots spaced
one month apart.
AstraZeneca agreed in April to co-develop Oxford's technology
and distribute it around the world at no profit through 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 hoped for initially, 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 behind
rivals 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 firstname.lastname@example.org and Jenny
Strasburg at email@example.com
(END) Dow Jones Newswires
December 30, 2020 06:38 ET (11:38 GMT)
Copyright (c) 2020 Dow Jones & Company, Inc.