RELATED: These Are the Symptoms of the Omicron Variant, South African Doctor Says. During a Dec. 1 White House news briefing, top COVID adviser Anthony Fauci, MD, confirmed that the first case of the Omicron variant was just discovered in the U.S., after having been identified in a fully vaccinated traveler who returned from South Africa to San Francisco, California, on Nov. 22 and tested positive for COVID on Nov. 29.ae0fcc31ae342fd3a1346ebb1f342fcb According to Fauci, the variant’s arrival in the U.S. is just another reason why vaccinated people should get their booster shot now, CNN reported. Vaccine manufacturers are already working to create variant-specific vaccines, but Fauci said that vaccinated people should not wait for a targeted booster when they can get added protection now. “Right now, I would not be waiting. People say, ‘Well, if we’re going to have a variant-specific booster, should we wait?’ If you are eligible—think six months with a double mRNA dose or two months for the J&J—get boosted now,” he said, per CNN. Pfizer, Moderna, and Johnson & Johnson manufacturers have all announced that they are working on vaccines that are specifically tailored to target the Omicron variant in case their existing shots are not effective against the new iteration of COVID, Reuters reported on Nov. 29. But according to CBS News, both Pfizer and Moderna said it would likely take at least three months to produce a new COVID vaccine for this variant. “We may not need a variant-specific boost. We’re preparing for the possibility that we need a variant-specific booster and that’s what the companies are doing,” Fauci said during the briefing. “But the mistake people would make is to say, ‘Let me wait to see if we get one.’” RELATED: For more up-to-date information, sign up for our daily newsletter. Virus experts are concerned that Omicron might bypass some of the protection offered by existing COVID vaccines because of the large number of mutations this variant has in relation to the spike protein, which is what the vaccines target. But according to Fauci, data has already shown that a booster dose of any of the three vaccines authorized in the U.S. significantly raises vaccinated people’s antibody levels. “And people ask, why is that important? Because our experience with variants such as the Delta variant is that even though the vaccine isn’t specifically targeted to the Delta variant, when you get a high enough level of an immune response, you get spillover protection even against a variant that the vaccine wasn’t specifically directed at,” the infectious disease expert explained. If Omicron does end up evading the effectiveness of some of these existing vaccines, the booster will still offer a stronger level of protection that just one or two doses. “That’s the reason why we feel even though we don’t have a lot of data on it, there’s every reason to believe that that kind of increase that you get with the boost would be helpful, at least in preventing severe disease of a variant like Omicron,” Fauci added. RELATED: This Is How Long Your Booster Will Last, New Study Says.