New York: The researchers have so far found just a single case of this formidable combination, but genetic analysis suggested that the variant had been acquired in the community and did not arise in the patient.

The variant originally identified in Britain, called B.1.1.7, has been spreading rapidly across the United States, and accounts for at least 2,500 cases in 46 states. This form of the virus is both more contagious and more deadly than the original version, and it is expected to account for most U.S. infections in a few weeks.

The new version that surfaced in Oregon has the same backbone, but also a mutation — E484K, or “Eek” — seen in variants of the virus circulating in South Africa, Brazil and New York City.