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Early data shows Pfizer vaccine less effective against Omicron

South African researchers say people who recovered and were vaccinated are largely protected against the new variant, vaccination alone still likely to prevent severe disease

Amy Spiro is a reporter and writer with The Times of Israel.

A lab technician works inside a pathological lab equipped to screen COVID-19 coronavirus patients and patients infected with the Omicron variant arriving from listed high risk destinations at a government hospital in Chennai, on December 6, 2021. (Arun Sankar/AFP)
A lab technician works inside a pathological lab equipped to screen COVID-19 coronavirus patients and patients infected with the Omicron variant arriving from listed high risk destinations at a government hospital in Chennai, on December 6, 2021. (Arun Sankar/AFP)

A study of early data from the Omicron COVID variant suggests that those with the Pfizer vaccine are significantly less protected against it than against previous strains of the disease.

The research, carried out by the South Africa-based Africa Health Research Institute, showed that the Omicron variant “escapes antibody immunity induced by the Pfizer-BioNTech (Comirnaty) vaccine.”

Alix Segal, a professor at AHRI and the author of the study, tweeted that the data shows a “large drop” in the vaccine’s efficacy against the Omicron variant.

Those involved with the study — which has not been peer-reviewed and examined blood samples from 12 participants — cautioned against drawing conclusions from the data.

“The clinical implications of these important laboratory data need to be determined,” said AHRI executive director Willem Hanekom. “It is likely that lesser vaccine-induced protection against infection and disease would be the result. Importantly, most vaccinologists agree that the current vaccines will still protect against severe disease and death in the face of Omicron infection. It is therefore critical that everyone should be vaccinated.”

The study noted that five out of six people who had been both previously infected and received two vaccines retain “considerable immunity” against the Omicron variant.

A woman gets a dose of the COVID-19 vaccine at a vaccine center in Jerusalem on November 28, 2021. (Olivier Fitoussi/Flash90)

“Previous infection, followed by vaccination or booster, is likely to increase the neutralization level and likely confer protection from severe disease in Omicron infection,” the study concludes.

There were no participants included in the study who had received three doses of the vaccine, since booster shots are not yet available in South Africa.

“These results are better than I expected,” tweeted Sigal. “The more antibodies you got, the more chance you’ll be protected from Omicron.”

There are at least 21 confirmed cases of the Omicron variant in Israel. As of Wednesday morning, more than 62 percent of all Israelis had received two doses of a COVID vaccine, and more than 44% had received three doses.

Top US scientist Anthony Fauci said on Tuesday that while it will take weeks to judge the severity of Omicron, early indications suggest it is not worse than prior strains, and possibly milder.

A preliminary study released last week by the South African DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis suggested that the Omicron variant was three times more likely to cause reinfections compared to the Delta or Beta strains.

AFP contributed to this report.

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