By Jenny Strasburg
LONDON -- AstraZeneca PLC and the University of Oxford added
their vaccine candidate to a growing list of shots showing
promising effectiveness against Covid-19 -- setting in motion
disparate regulatory and distribution tracks that executives and
researchers hope will result in the start of widespread
vaccinations by the end of the year.
AstraZeneca and Oxford said their vaccine was as much as 90%
effective in preventing the infection without serious side effects
in large clinical trials, though they said the vaccine's efficacy
varied widely based on dosage.
At the lower end, the vaccine's 62% efficacy trailed the trial
results issued by rival drugmakers so far. The limited results at
the top end of the range, however, came close to matching those of
two other Western-developed vaccine candidates, one from Moderna
Inc. and one from Pfizer Inc. and Germany's BioNtech SE. Each of
those showed efficacy of more than 90% in early results disclosed
recently.
These preliminary findings, all from so-called Phase 3 human
trials, represent the first look at the effectiveness of
experimental Covid-19 vaccines and open the way for the companies
to seek regulatory authorization and gear up their distribution
plans. That process is now under way for all three of the West's
front-runner vaccine candidates, though at different speeds in
different parts of the world.
"If there is anyone out there who still doubts that a Covid-19
vaccine can help us out of this pandemic, the announcement
today...should surely dispel that doubt," said Prof. Eleanor Riley,
an immunology and infectious-disease expert at Scotland's
University of Edinburgh.
China and Russia have both deployed their own vaccines at home
and overseas. Chinese authorities have inoculated nearly one
million Chinese people with a vaccine from one state company,
though it has yet to provide solid clinical evidence of its
efficacy. Russia has said its own homegrown vaccine has an efficacy
rate of above 90%.
Pfizer said last week it had submitted its vaccine to the U.S.
Food and Drug Administration for approval for emergency use, a
route that has expedited approval for several Covid-19 treatments.
That puts Pfizer and partner BioNtech in the pole position for
winning authorization in the U.S. first. The FDA hasn't specified a
timeline for approval, but it could come within weeks, followed by
the start of vaccinations shortly thereafter.
Moderna is right behind Pfizer and could make a submission as
early as next month. It has said it could start rolling out its
vaccine the same month.
AstraZeneca is further behind in the U.S. since the large-scale
trials disclosed Monday were conducted in the U.K. and Brazil, not
in the U.S. AstraZeneca's trials in the U.S. were temporarily
halted after a British trial subject fell ill.
The company, which is based in Cambridge, U.K., said Monday it
would seek permission to modify its U.S. trials, to provide for
more testing of the dosage regimen that proved the most effective
in its U.K. and Brazil trials. That could take several weeks,
setting back possible FDA approval.
The AstraZeneca-Oxford vaccine has some advantages that experts
say could make for a faster rollout outside the U.S., after
regulatory approval, particularly in the developing world. The
partners committed to selling it without profit during the pandemic
and promised to distribute it across a much wider geographic
footprint, including in large parts of the developing world. The
shot is expected to cost $3 to $5 a dose globally during the
pandemic, and AstraZeneca has committed to supplying some three
billion doses by 2022.
The shot was created from a more traditional vaccine methodology
compared with the gene-based technology used by Moderna and Pfizer.
The Oxford-AstraZeneca shot doesn't need to be stored in subzero
temperatures, making its rollout easier, researchers and logistics
experts say.
"A particular strength of this vaccine is that it can be stored
in a fridge," said Prof. Azra Ghani, chair in infectious disease
epidemiology at Imperial College London. "This means that it can be
distributed around the world using existing delivery
mechanisms."
AstraZeneca said it would seek emergency-use authorization from
the World Health Organization to distribute the vaccine in
low-income countries and prepare regulatory submissions to
authorities in countries that have early-approval programs.
Pending regulatory authorization, the shot could be available in
limited volumes by year-end, with hundreds of millions more doses
available in the first few months of next year, AstraZeneca
executives said. The level of output depends on manufacturers
across the world that are working with AstraZeneca to produce the
vaccine.
The European Medicines Agency, which authorizes new medicines
for sale in the European Union, said in early October that it had
begun a rolling review of the Oxford vaccine to speed up a
potential approval. A rolling review allows regulators to evaluate
preliminary data such as those from lab experiments before
final-stage clinical trials are completed.
Officials in the U.K., which is transitioning out of the EU, say
they have the power to authorize use of a Covid-19 vaccine in the
country before year-end, if they choose. The U.K. also has been
reviewing Oxford and AstraZeneca data on a rolling basis since
early November. Canada has also begun a rolling review of the
vaccine.
Monday's results from AstraZeneca and Oxford left big questions
about how the vaccine will ultimately stack up against the shots
from Moderna and Pfizer. The higher efficacy result of 90% applied
to a subset of trial participants -- somewhere above 3,000 out of
about 23,000 -- that received half a dose of the vaccine followed
by a full, standard dose. The remaining bulk of trial volunteers
received two full doses and produced the lower efficacy result of
62%.
Prof. Sarah Gilbert, one of Oxford's lead scientists on the
vaccine, said researchers are digging into why the half-dose
regimen was shown to be more effective. She said it could be that
the lower first dose better mimics the natural human immune system,
coaxing the body to be ready for an eventual fight against the
virus in a way that makes the second, standard dose more
effective.
Two-dose vaccines often behave differently from single-dose
vaccines, Oxford scientists said. With the latter, a stronger dose
is usually closely matched with higher efficacy. With two doses,
the first dose acts as a primer for the second dose.
In an interview last week about broader vaccine concerns, Jeremy
Farrar, director of the Wellcome Trust, a U.K.-based global health
foundation and backer of Oxford's vaccine research, said his
biggest worry overall about access to vaccines is that the
highest-quality shots will be narrowly available.
Of possible scenarios, Dr. Farrar said, "the one that worries me
the most, I suppose, is this sense that there'll be poor vaccines
for poor people, either in country or between countries."
He and others point out massive efforts to fund vaccine
purchases for low- and middle-income countries. However, volume
limits could still constrain global access.
The Wellcome Trust's head of vaccines, Dr. Charlie Weller,
called the Oxford-AstraZeneca results "hugely encouraging." The
preliminary efficacy results suggest the vaccine is "highly
effective in protecting serious illness and it may reduce
transmission," Dr. Weller said.
Some Wall Street analysts said the results would likely mean the
Oxford-AstraZeneca vaccine finds global use, but possibly with
adoption focused in poorer countries.
The vaccine's ease of storage "and very low price still likely
assures significant global use, especially in less developed
countries," Citigroup Inc. healthcare analyst Andrew Baum said in a
research note that called the results "underwhelming."
The dosage that resulted in 90% efficacy wasn't convincing given
its small sample size and the lack of a clear explanation by Oxford
and AstraZeneca of the "biologic rationale" of pairing a half-dose
with a full dose, Mr. Baum wrote in his note. Furthermore, he said
the early results could hurt AstraZeneca's ability to finish
recruiting participants for ongoing U.S. late-stage trials.
Some researchers said it will be important to compare the
effectiveness and safety of the leading vaccine candidates. Oxford
and AstraZeneca officials said such comparisons are difficult at
this stage, but added that different shots are likely to be
effective in different people -- a result that scientists expect to
be a positive for fending off serious Covid-19 symptoms and halting
the virus's spread.
Like with other Covid-19 vaccines in development, researchers
don't yet know how long the positive effects of the shot last,
which is key to understanding the required frequency of
vaccination. It will also affect overall effectiveness in
preventing the spread of the disease and helping jump-start
stricken economies.
Write to Jenny Strasburg at jenny.strasburg@wsj.com
(END) Dow Jones Newswires
November 23, 2020 13:26 ET (18:26 GMT)
Copyright (c) 2020 Dow Jones & Company, Inc.
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