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Moderna warns of material drop in vaccine efficacy against Omicron


The Moderna CEO says existing COVID-19 vaccines will likely be less effective against the new Omicron variant.

“There is no world, I think, where [the effectiveness] is the same level … we had with Delta,” Stephane Bancel told the Financial Times .

“I think it’s going to be a material drop,” he said. “I just don’t know how much, because we need to wait for the data. But all the scientists I’ve talked to … are like, ‘This is not going to be good.’”

Vaccine companies are now studying whether the new Omicron variant could evade the current shots. Some data is expected in about 2 weeks.

Mr. Bancel said that if a new vaccine is needed, it could take several months to produce at scale. He estimated that Moderna could make billions of vaccine doses in 2022.

“[Moderna] and Pfizer cannot get a billion doses next week. The math doesn’t work,” he said. “But could we get the billion doses out by the summer? Sure.”

The news caused some panic on Nov. 30, prompting financial markets to fall sharply, according to Reuters. But the markets recovered after European officials gave a more reassuring outlook.

“Even if the new variant becomes more widespread, the vaccines we have will continue to provide protection,” Emer Cooke, executive director of the European Medicines Agency, told the European Parliament.

Mr. Cooke said the agency could approve new vaccines that target the Omicron variant within 3 to 4 months, if needed. Moderna and Pfizer have announced they are beginning to tailor a shot to address the Omicron variant in case the data shows they are necessary.

Also on Nov. 30, the European Centre for Disease Prevention and Control announced that 42 Omicron cases had been identified in 10 European Union countries, according to Reuters.

The cases were mild or had no symptoms, although they were found in younger people who may have mild or no symptoms anyway.

“For the assessment of whether [Omicron] escapes immunity, we still have to wait until investigations in the laboratories with [blood samples] from people who have recovered have been carried out,” Andrea Ammon, MD, chair of the agency, said during an online conference.

The University of Oxford, which developed a COVID-19 vaccine with AstraZeneca, said Nov. 30 that there’s no evidence that vaccines won’t prevent severe disease from the Omicron variant, according to Reuters.

“Despite the appearance of new variants over the past year, vaccines have continued to provide very high levels of protection against severe disease and there is no evidence so far that Omicron is any different,” the university said in a statement. “However, we have the necessary tools and processes in place for rapid development of an updated COVID-19 vaccine if it should be necessary.”

A version of this article first appeared on

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