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Pfizer Chairman and CEO Albert Bourla said Wednesday people may need a fourth dose of the COVID vaccine sooner than expected after preliminary research showed the Omicron variant can undermine antibody protection in people with only two doses.

Pfizer and BioNTech released results from their initial lab study showing a third dose was protective against the new variant, but the initial two-dose series dropped significantly in its ability to protect against the new strain.

The two-dose series may still offer protection against severe sickness from Omicron, the companies claimed.

“Three doses against Omicron are almost equivalent to the two doses’ effectiveness against … the original variant,” Bourla said in an interview with TODAY. “If we need a new vaccine … we will be able to have a very good one.”

Bourla said the preliminary study was based on a synthetic, lab-created copy of the variant, and more data is needed from tests using the actual virus. Real-world results will be more accurate and are expected in the next two weeks, he said.

“When we see real-world data, we will determine if the Omicron is well covered by the third dose and for how long,” Bourla told CNBC’s “Squawk Box.” “And the second point, I think we will need a fourth dose.”

Bourla previously predicted a fourth dose would be needed 12 months after the third dose, but said with Omicron, “we may need it faster.”

Studies published in October in the New England Journal of Medicine confirmed any immune protection offered by two doses of Pfizer’s COVID vaccine drops off after roughly two months.

Bourla said what’s most important is the rollout of third doses of its COVID vaccine. He said the booster and its antiviral pill, paxlovid, will help control COVID during the winter.

“A third dose will give very good protection I believe,” Bourla said, “and treatments such as Pfizer’s oral antiviral pill, paxlovid, will help prevent hospitalizations and control COVID during the winter.

Pfizer submitted its application to the U.S. Food and Drug Administration (FDA) for Emergency Use Authorization of paxlovid last month. The Biden administration purchased 10 million courses of the drug even though the FDA has not signed off on it.

Pfizer stocks rose Wednesday amid news the company’s COVID vaccine works against the Omicron variant after three doses.

“[There is] great news from Pfizer that a booster will work in adding solid protection against Omicron and stocks are celebrating,” said Peter Boockvar, chief investment officer of Bleakley Advisory Group.

As The Defender reported Tuesday, Global Justice Now released data showing “just eight top Pfizer and Moderna shareholders” and their CEOs made $10.31 billion since Omicron, emerged — despite reports, including by the doctor who discovered the variant, that it’s mild and may even be useful for achieving herd immunity.

Fauci: definition of ‘fully vaccinated’ will change to include third dose

It’s only a matter of time before the definition of fully vaccinated is changed to include a third dose, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Wednesday.

“Right now, I don’t see that changing tomorrow or next week,” Fauci said during an appearance on CNN, but added that in his opinion, “it’s going to be a matter of when not if.”

“Certainly, when you want to talk about what optimal protection is, I don’t think anybody would argue that optimal protection is going to be with a third shot,” Fauci said, but it’s a “technical, almost semantic definition, and it is the definition for requirements.”

According to the Centers for Disease Control and Prevention (CDC) website, “fully vaccinated persons are those who are ≥14 days post completion of the primary series of an FDA-authorized COVID-19 vaccine.”

The term fully vaccinated refers to a person who has received two doses of Pfizer or Moderna COVID vaccines or a single shot of Johnson & Johnson.

Fauci previously said changing the definition of what qualifies a person as fully vaccinated to include a booster shot was “on the table.”

Dr. Rochelle Walensky, director of the CDC — which determines the definition for fully vaccinated — said in October she was open to the possibility of changing the definition when the booster rollout began.

The definition has implications because it is used by those imposing vaccine mandates across the country, including federal mandates for healthcare workers, government contractors and private businesses with more than 100 employees.

Fauci said the timing of the change may be related to the ongoing cases. “It has implications for that, and that’s the reason why it matters,” Fauci said.