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Jab only partially effective on Omicron: study | Blue Mountain Gazette


The Omicron variant may partially escape the protection of two doses of Pfizer’s COVID-19 vaccine, according to the research director of a laboratory in South Africa.

Alex Sigal, a professor at the Africa Health Research Institute, said on Twitter that there was “a very large drop” in neutralization of the Omicron variant compared to an earlier strain of COVID-19.

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 lab tested the blood of 12 people who had been vaccinated with two doses of the Pfizer-BioNTech vaccine, according to a manuscript published on its official 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 The preliminary manuscript data has not yet been peer reviewed.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.”

The Omicron variant, first detected in southern Africa last month, has raised global alarms for a new wave of infections, with more than two dozen countries reporting cases.

The World Health Organization listed Omicron on Nov. 26 as a “variant of concern,” but said there was no evidence to support the need for new vaccines.

There is no significant data yet on how vaccines from Moderna, Johnson & Johnson and other drugmakers are resistant to the new variant. All manufacturers, including Pfizer, are expected to release their own data in a few weeks.

U.S. infectious disease expert Dr Anthony Fauci said on Tuesday that preliminary evidence indicates that Omicron likely has a higher degree of transmissibility but is less severe.

Umer Raffat, analyst for Evercore ISI, cautioned against over-reading a single study, noting that there was significant variability in the measurement of declines in antibody levels in previous lab studies.

“Let’s wait for further studies to draw a mosaic,” he said.

Australian Associated Press