CDC Director Dr. Rochelle Walensky told reporters Tuesday her agency is heightening its screening measures at the four major airports and working with airlines to gather contact information for passengers, should a case of the variant be identified in a passenger.
Dr. Walensky says the US has significantly expanded its genomic sequencing and is now sequencing up to 80,000 viral samples a week, and screening about 1 out of every seven PCR tests collected.
"We are actively looking for the omicron variant right here in the United States," Dr. Walensky says. "Right now there is no evidence of omicron in the United States. The delta variant remains the dominant strain, representing 99.9% of all sequenced samples."
The new variant, which surfaced in mid-November in Botswana and then South Africa, has raised alarm because it carries a very high number of genetic mutations — about 50 of them — that could make it more transmissible and render the current COVID-19 vaccines less effective.
Still, Dr. Anthony Fauci says, the vaccines will likely provide some level of cross-protection against the variant, especially for those who receive a booster dose.
"So, there’s every reason to believe, as we talk about boosters, when you get a level high enough, that you are going to get at least some degree of cross-protection, particularly against severe disease," Fauci says.
With the small number of cases, he says, it is difficult to know whether the variant is capable of causing more severe symptoms.
"Although some preliminary information from South Africa suggests no unusual symptoms associated with the variant, we do not know and it is too early to tell," Fauci says.
The World Health Organization has labeled omicron a Variant of Concern, saying it poses a very high risk of spreading.
Dr. Fauci says it will take another two to four weeks before scientists have definitive answers about how much of a threat the variant will pose.
The US imposed travel restrictions Monday, barring many travelers from southern Africa, hoping to buy the country some time to vaccinate more Americans.
Nearly 60% of Americans are now fully vaccinated, but 45 million people eligible for the shots remain unvaccinated.
White House Coronavirus Response Coordinator Jeff Zients urged Americans to get both the initial vaccine and booster shot, if eligible, as soon as possible.
"More than 100 million adults are now eligible for a booster but have not yet gotten one," Zients says. "Our message is simple: If you were fully vaccinated before June, go get a booster shot today. Getting boosted will give you the highest level of protection from COVID and from this new variant."