The new COVID-19 variant that was discovered in the UK "could already be" in the US without having been detected, the Centers for Disease Control and Prevention (CDC) said Tuesday.
The health agency said ongoing travel between countries and the high prevalence of the variant among current UK infections increase the likelihood of importation.
"Given the small fraction of US infections that have been sequenced, the variant could already be in the United States without having been detected," said the CDC.
Only about 51,000 of 17 million cases have been sequenced so far, according to the agency.
Several countries have banned flights from the UK because of the new variant, which is thought to be spreading 70% faster than the previous strain. But there has been no evidence it is more likely to cause severe disease or mortality.
"Although a variant may predominate in a geographic area, that fact alone does not mean that the variant is more infectious," said the CDC.
"Scientists are working to learn more about this variant to better understand how easily it might be transmitted and whether currently authorized vaccines will protect people against it," it added.
