Dec. 7 (Reuters) – The Omicron variant may partially escape protection against two doses of Pfizer (PFE.N) and the COVID-19 vaccine from its partner BioNTech, the research director of a laboratory at the Africa Health Research Institute in South Africa.

But the study showed that the blood of people who received two doses of the vaccine and had a previous infection was mainly able to neutralize the variant, suggesting that booster doses of the vaccine might help fend off the infection.

The Omicron variant, first detected in southern Africa last month, has raised global alarms of a new wave of 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 combat the Omicron variant with its many mutations. Read more

Alex Sigal, a professor at the research institute, said on Twitter that there had been “a very large drop” in neutralization of the Omicron variant compared to an earlier strain of COVID-19.

A separate lab test by virologist Sandra Ciesek of the University Hospital in Frankfurt painted a somewhat darker picture.

By exposing the blood of vaccinated individuals to different viral variants, she found that the ability to elicit an antibody response to Omicron in people who received three injections of BioNTech / Pfizer was up to 37 times lower than the response to Delta. .

An antibody response to Omicron six months after a two-shot regimen of Pfizer / BioNTech, Moderna or a mixed cycle of AstraZeneca / BioNTech was not even measurable, Ciesek added.

She only posted selected results on Twitter, not counting the number of samples, and the university said the article had not yet been published.

“The dataset underscores that it makes sense to develop a suitable vaccine for Omicron,” Chiesek tweeted, adding that no conclusion could be drawn about protection against serious disease.

WHO chief scientist Soumya Swaminathan said a sharp drop in the antibody response of people vaccinated against Omicron is expected.

“That doesn’t mean the vaccine won’t work – T-cell immunity (is) likely to persist,” she said on Twitter, referring to a cellular immune response believed to prevent serious disease as a second line of immune defense.

Researchers including Carsten Watzl of the German Society for Immunology and Penny Ward, visiting professor at King’s College London, said the findings underscored the need for booster shots, as a three-shot course would likely continue to protect against serious illnesses.

Sigal’s lab tested the blood of 12 people who had been vaccinated with two doses of the Pfizer / BioNTech vaccine, according to a manuscript posted on his lab’s website. The preliminary manuscript data has not yet been peer reviewed.

The blood of five out of six people who had been vaccinated as well as previously infected with COVID-19 still neutralized the Omicron variant, according to the manuscript.

“These results are better than I expected. The more antibodies you have, the more likely you are to be protected against Omicron,” Sigal said on Twitter.

He said the lab had not tested the variant against the blood of people who received a booster dose, as they were not yet available in South Africa.

According to the manuscript, the lab observed a 41-fold drop in neutralizing antibody levels against the Omicron variant.

Sigal said on Twitter that this figure will likely be adjusted after his lab does more experiments.

While neutralizing antibodies are an indicator of the body’s immune response, scientists believe that other types of cells such as B cells and T cells are also stimulated by vaccines and help protect against the effects of the coronavirus.

Preliminary data does not indicate that the vaccine is less able to prevent serious illness or death. While lab tests are ongoing, BioNTech CEO Ugur Sahin said last week “we believe it is likely that people will benefit from substantial protection against serious illnesses caused by Omicron.” Read more

There is no significant data yet on how vaccines from Moderna (MRNA.O), Johnson & Johnson (JNJ.N) and other drugmakers are resistant to the new variant. All manufacturers, including Pfizer and BioNTech, are expected to release their own data within a few weeks.

BioNTech’s Sahin told NBC News on Tuesday that the drugmaker had data coming 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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