The Omicron variant of the coronavirus has been found in about 15 US states so far, but the Delta variant remains the majority of Covid-19 cases nationwide.
"We know we have several dozen cases and we're following them closely. And we are every day hearing about more and more probable cases so that number is likely to rise," CDC Director Dr Rochelle Walensky said on Sunday, adding more data is still needed.
Speaking during an interview with ABC's ''This Week'' programme, Walensky said Delta accounted for most cases in the United States and as vaccines are known to protect against hospitalisation and death, health officials hope they will blunt the impact of Omicron as well.
She said that of the 90,000 to 100,000 cases a day, 99.9 percent of them are the Delta variant.
"We have an issue right now in the United States about Delta," Walensky stated.
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Omicron cases
The 15 states that have reported Omicron cases are California, Colorado, Connecticut, Hawaii, Maryland, Massachusetts, Minnesota, Missouri, Nebraska, New Jersey, New York, Pennsylvania, Utah, Washington and Wisconsin, according to Reuters news agency tally.
Louisiana has also reported a probable case, while the person reported in New Jersey had also previously traveled to Georgia, which also reported the positive test.
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