By Jenny Strasburg
LONDON -- AstraZeneca PLC and the University of Oxford said
their Covid-19 vaccine was as much as 90% effective in preventing
infections without serious side effects in large clinical trials,
boosting hopes that a third Western-developed shot could be
authorized for use before the end of the year.
The partners said Monday that there were no serious safety
events related to the vaccine and that it was well tolerated across
different dosing regimens. Its efficacy ranged from 62% to 90%
depending on the dosage given, with an average of 70%, they
said.
The results bode well for the near-term availability of a third
vaccine to battle Covid-19, after a shot created by Moderna Inc.
and one made jointly by Pfizer Inc. and Germany's BioNTech SE were
found to be more than 90% effective in their own late-stage trials.
Pfizer and BioNTech last week said they had asked the U.S. Food and
Drug Administration to permit use of their vaccine.
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%.
AstraZeneca and Oxford's vaccine stands out among the leading
Western candidates. 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 was created from a more traditional vaccine methodology
than the gene-based technology used by Moderna and Pfizer. As such,
it doesn't need to be stored in subzero temperatures, making its
rollout potentially easier.
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. A
senior AstraZeneca executive said Friday the company hopes to have
the two-dose shot available for use around year-end, pending
regulatory approval.
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
U.K. before year-end, if they choose. The U.K. also has been
reviewing Oxford and AstraZeneca's data on a rolling basis since
early November. Canada has also begun a rolling review of the
vaccine.
Trials of the vaccine, called AZD1222, were held in the U.K. and
Brazil. Late-stage clinical trials of the vaccine are continuing in
the U.S. following a trial pause there that spanned most of
September and October. AstraZeneca wouldn't likely apply for
approval from the FDA until those trials have shown results.
The results released Monday were based on trials involving more
than 23,000 participants. Individuals who received the vaccine
received one of two combinations: a half dose followed by a full
dose, which showed to be 90% effective; or two full doses, which
showed to be 62% effective. Researchers said Monday the preliminary
results are promising but will need to be fleshed out before
scientists can understand why the half-dose regimen was more
effective.
Oxford's chief investigator in the trials, Prof. Andrew Pollard,
said the results mean the vaccine "may be around 90% effective." He
said the regimen using a half dose for the first dose would also
mean more people could be vaccinated with planned supplies.
As trials continue, Oxford and AstraZeneca will continue to
refine the efficacy readings, helping determine whether the
more-positive results hold up across a broader population of
participants. The Oxford-AstraZeneca vaccine trials ultimately will
enroll as many as 60,000 participants globally. The U.K. drugmaker
said that the full analysis of the results is being submitted for
peer review.
A full review of broader global trial results and full safety
data are still to come.
Some researchers also said that it will be important to compare
the effectiveness and safety of the leading vaccine candidates side
by side.
AstraZeneca Chief Executive Pascal Soriot said the company is
poised to make hundreds of millions of doses of the vaccine
available upon regulatory approval.
A major question the researchers can't yet answer is how long
the positive effects of the vaccine last. That question for all
eventual Covid-19 vaccines is key to understanding how long
immunity might last, which will affect the required frequency of
vaccination. It will also affect overall effectiveness in
preventing the spread of the disease and helping jump-start
stricken economies.
Oxford and AstraZeneca's vaccine uses a more traditional
approach than the Moderna and Pfizer shots, which both rely on a
new technology called messenger RNA to induce an immune response
inside the body. AstraZeneca's vaccine instead relies on
introducing a weakened, chimpanzee virus into the body to trigger
the immune response.
"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."
Oxford invented the vaccine along with a company spun out of the
university called Vaccitech Ltd. In April, Vaccitech relinquished
its rights to the vaccine to Oxford in exchange for a small slice
of potential future royalties, enabling Oxford's exclusive deal
with AstraZeneca.
In May, Oxford started Phase 2 and 3 human trials, and
AstraZeneca in late August launched a large, final-stage U.S. study
aiming to enroll 30,000 volunteers to test the vaccine. The study
was paused in early September after a patient in a U.K. trial
suffered from an unexplained illness. The FDA permitted the U.S.
study to resume Oct. 23. The separate, final-stage trial in the
U.K. also paused but was restarted within less than a week.
An independent safety committee determined the illness was
either unrelated to the vaccine, or couldn't be linked to the
vaccine because of a lack of information to determine a connection,
according to an information sheet given to study volunteers and
posted online by the University of Oxford.
Later, a participant in trials of the vaccine in Brazil died,
but the country's health regulator immediately said the trials
would continue. At the time, Oxford said it had carried out an
assessment of the case in Brazil and that there were no concerns
about the safety of the trial. An independent assessment of the
case didn't present any concerns, AstraZeneca said.
Write to Jenny Strasburg at jenny.strasburg@wsj.com
(END) Dow Jones Newswires
November 23, 2020 05:37 ET (10:37 GMT)
Copyright (c) 2020 Dow Jones & Company, Inc.
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