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 But the study showed that blood from people who had received two
doses of the vaccine and had a prior infection was mostly able to
neutralize the variant, suggesting that booster doses of the vaccine
could help to fend off infection.
The Omicron variant, first detected in southern Africa last month,
has triggered alarms globally of another surge in infections, with
more than two dozen countries from Japan to the United States
reporting cases.
The World Health Organization classified it on Nov. 26 as a "variant
of concern," but said there was no evidence to support the need for
new vaccines specifically designed to tackle the Omicron variant
with its many mutations.
Alex Sigal, a professor at the research institute, said on Twitter
there was "a very large drop" in neutralization of the Omicron
variant relative to an earlier strain of COVID-19.
A separate lab test by virologist Sandra Ciesek of the University
Hospital Frankfurt painted a somewhat bleaker picture.
Exposing the blood of vaccinated individuals to different virus
variants, she found that the ability to mount an antibody response
to Omicron in people who had three shots of BioNTech/Pfizer was up
to 37 times lower than the response to Delta.
An antibody response to Omicron half a year after a two-shot regimen
of Pfizer/BioNTech, Moderna or a mixed course of AstraZeneca/BioNTech
was not even measurable, Ciesek added.
She posted only selected findings on Twitter, not including the
number of samples, and the university said the paper had not yet
been published.
"The set of data underscores that it makes sense to develop a
vaccine that is adapted to Omicron," Chiesek tweeted, adding that no
conclusion could be drawn about protection against severe disease.
WHO's chief scientist, Soumya Swaminathan, said a large drop in the
antibody response of vaccinated people to Omicron had been expected.
"This does not mean the vaccine will not work - T-cell immunity (is)
likely to persist," she said on Twitter, referring to a cellular
immune response that is believed to prevent severe disease as a
second line of immune defence.
Researchers including Carsten Watzl of the German Society of
Immunology and Penny Ward, visiting professor at King’s College
London, said the findings underscored the need to get booster shots
because a three-shot course would likely continue to protect against
severe disease.
[to top of second column] |
 Sigal's lab tested blood from
12 people who had been vaccinated with two doses
of the Pfizer/BioNTech vaccine, according to a
manuscript posted on the website for his lab.
The preliminary data in the manuscript has not
yet been peer reviewed.
Blood from five out of six people who had been
vaccinated as well as previously infected with
COVID-19 still neutralized the Omicron variant,
the manuscript said.
"These results are better than I expected. The
more antibodies you got, the more chance you'll
be protected from Omicron," Sigal said on
Twitter.
He said the lab had not tested the variant
against blood from people who had received a
booster dose, because they are not available in
South Africa yet.
According to the manuscript, the lab observed a
41-fold decline in levels of neutralizing
antibodies against the Omicron variant.
Sigal said on Twitter that figure is likely to
be adjusted after his lab does more experiments.
While neutralizing antibodies are an indicator
of the body's immune response, scientists
believe other kinds of cells such as B-cells and
T-cells are also stimulated by the vaccines and
help protect against the effects of the
coronavirus.
The preliminary data does not indicate that the
vaccine is less able to prevent severe illness
or death. While lab tests are under way,
BioNTech CEO Ugur Sahin said last week "we think
it's likely that people will have substantial
protection against severe disease caused by
Omicron".
There is not significant data yet on how
vaccines from Moderna, Johnson & Johnson and
other drugmakers hold up against the new
variant. All the manufacturers, including Pfizer
and BioNTech, are expected to release their own
data within weeks.
BioNTech's Sahin told NBC News on Tuesday that
the drugmaker has data coming on Wednesday or
Thursday.
(Reporting by Manas Mishra in Bengaluru and
Michael Erman in New Jersey, Ludwig Burger in
Frankfurt; Editing by Shounak Dasgupta, Lisa
Shumaker, Peter Cooney, Kim Coghill and Nick
Macfie)
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