Pfizer Says Its Booster Is Effective Against Omicron

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“You have to start somewhere,” said Kathrin U. Jansen, a senior vice president and the head of vaccine research and development at Pfizer, while awaiting the results of more complex studies and “real-world evidence that tells you what we need to know.”

Scientists say it could take a month or more to really understand the new variant’s threat. By then, they say, Israel, Britain or other countries with sophisticated health surveillance systems will have gathered more data on whether Omicron will overtake Delta and how the vaccines will hold up against it.

The Pfizer-BioNTech results seemed to underscore the importance of boosters in combating infection. The blood samples obtained from people who had received a booster shot contained antibodies neutralizing Omicron at levels comparable to those combating the original variant after two doses, Pfizer’s statement said.

While calling the results “really good news,” Dr. Peter Hotez, a vaccine expert with the Baylor College of Medicine, noted that researchers only measured the levels of neutralizing antibodies one month after a booster injection. He is concerned, he said, that the surge of virus-blocking antibodies provided by a booster may be short-lived.


Dec. 8, 2021, 9:17 p.m. ET

The World Health Organization, which has long resisted broad rollouts of booster shots amid severe vaccine shortages in poorer nations, said on Wednesday that it was too early to conclude whether the vaccines were significantly less effective against Omicron or whether the emergence of the variant necessitated a booster shot for most people.

Both Dr. Albert Bourla, the chief executive officer of Pfizer, and Dr. Ugur Sahin, the chief executive of BioNTech, said that while two doses may still prevent severe disease from Omicron, the study demonstrates that a third strengthens protection. Dr. Sahin said three doses “could still offer a sufficient level of protection from disease of any severity” caused by the variant. Like other vaccine manufacturers, both companies have profited hugely from the global demand for their shots.

The companies suggested that Omicron would not significantly diminish the power of T-cells, which kill off infected cells. Researchers identified parts of Omicron that could be recognized by the T-cells produced after vaccination. Most did not contain any mutations.