WASHINGTON, Dec 3 (Reuters) - COVID-19 vaccine makers have contingency plans to deal with the Omicron variant that include a combination vaccine against the original version and the variant as well as a variant-specific booster dose, a top U.S. health official said on Friday. The U.S. government is working with Moderna, Pfizer (PFE.N), and J&J (JNJ.N) on multiple contingency plans, infectious disease expert Anthony Fauci told reporters at a White House briefing."One is to rev up the production of the vaccines that they already have. The next is to make, for example, a bivalent, where you have the vaccine against both the ancestral strain and the new variant, and the other is to make a variant-specific boost," said Fauci. "They are now assuming they may have to do that and are being prepared for that," he added.Data from a National Institutes of Health study strongly suggest that existing boosters provide cross protection against a number of variants, including Omicron, Fauci said. "Although we haven"t proven it yet, there"s every reason to believe that if you get vaccinated and boosted that you would have at least some degree of cross protection, very likely against severe disease, even against the Omicron variant."The U.S. Centers for Disease Control and Prevention is working with local authorities to investigate suspect cases of the Omicron variant in states other than those where cases have already been reported, Director Rochelle Walensky said at the briefing. There have been cases of Omicron detected in about 40 countries, she said, but the Delta variant remains the dominant strain in the United States. "I know that the news is focused on Omicron. But we should remember that 99.9% of cases in the country right now are from the Delta variant. Delta continues to drive cases across the country, especially in those who are unvaccinated," she said.