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* First tests of vaccine against new variants encouraging
* Scientists say mutations will need constant monitoring
* Variants found in South Africa, Britain; more infectious
(Adds definition of spike protein, other details)
By Michael Erman
NEW YORK, Jan 7 (Reuters) - Pfizer Inc and
BioNTech's COVID-19 vaccine appears able to protect
against a key mutation in the highly transmissible new variants
of the coronavirus discovered in Britain and South Africa,
according to a laboratory study conducted by the U.S. drugmaker.
The study by Pfizer and scientists from the University of
Texas Medical Branch, which has not yet been peer-reviewed,
indicated the vaccine was effective in neutralizing variants
with the so-called N501Y mutation, situated on a portion of the
virus that it uses to enter and infect cells.
All of the vaccines already approved or in development use
this outer portion of the virus, known as the spike protein, to
train the body to recognize the virus and make
virus-neutralizing antibodies.
The N501Y mutation is linked to greater transmissibility,
and scientists have expressed concerns it could also allow the
virus to escape the neutralizing antibodies produced in response
to the vaccine, said Phil Dormitzer, one of Pfizer's top viral
vaccine scientists.
The first results of tests on some of the key variants of
concern offer some hope as Britain and other countries try to
tame the more infectious variants, which authorities believe are
driving a surge in infections that could overwhelm healthcare
systems.
Although all viruses mutate constantly, scientists are
concerned about the mutations first discovered in Britain and
South Africa because they are believed to be capable of altering
key functions of the virus.
The Pfizer study was conducted on blood taken from people
who had been given the vaccine. Its findings are limited because
it does not look at the full set of mutations found in either of
the new variants of the rapidly spreading virus.
Dormitzer said it was encouraging that the vaccine appears
effective against the mutation, as well as against 15 other
mutations the company has previously tested.
"So we've now tested 16 different mutations, and none of
them have really had any significant impact. That's the good
news," he said. "That doesn't mean that the 17th won't."
The study still does not address a worrisome mutation in the
South African variant, called the E484K mutation.
CONSTANT MONITORING
The U.S. researchers plan to run similar tests to see
whether the vaccine protects against other mutations from the
variants from Britain and South Africa. They hope to have data
within weeks.
The variants are said by scientists to be more transmissible
than previously dominant ones, but they are not thought to cause
more serious illness.
Independent experts gave a cautious welcome to the Pfizer
study findings, but said the situation needs constant vigilance.
Paul Hunter, a professor in medicine at Britain's University
of East Anglia, said "the jury is still out on the impact of the
South African variant on vaccine efficacy."
Deborah Dunn-Walters, a professor of immunology at Surrey
University in Britain, said it was "reassuring" that Pfizer is
closely monitoring variants.
Ongoing testing will be needed, experts said, to allay
concerns about whether vaccines being given to millions of
people in the fight against the pandemic will protect them as
the virus mutates. COVID-19 has killed more than 1.8 million
people worldwide.
"The evidence is not conclusive but there is a lot to
indicate that the existing mRNA vaccines do cover the new
variants. That is the good news," said Andreas Bergthaler,
principal investigator at the Research Center for Molecular
Medicine of the Austrian Academy of Sciences in Vienna.
TESTS AND TWEAKS
AstraZeneca, Moderna and CureVac
are also testing whether their shots will protect against the
fast-spreading coronavirus variants. They have said they expect
them to be effective, but have not said when study results will
be published.
The Pfizer/BioNTech COVID-19 vaccine and the one from
Moderna Inc, which both use synthetic messenger RNA technology,
or mRNA, can be quickly adapted to address new mutations in the
coronavirus if necessary. Scientists have suggested the changes
could be made in as little as six weeks.
Eleanor Riley, a professor of immunology and infectious
disease at Edinburgh University, said similar studies would need
to be repeated as new mutations appear. "It may be necessary to
tweak the vaccine over time," she said.
A senior British lawmaker expressed concerns in an interview
on Friday that COVID-19 vaccines might not work properly against
the South African variant. He was not responding to questions
about Friday's data.
(Additional reporting by Kate Kelland in London, Julie
Steenhuysen in Chicago and Doug Busvine in Berlin; Writing by
Josephine Mason; Editing by Bill Berkrot, Edwina Gibbs, Timothy
Heritage and Dan Grebler)
