Public health experts weigh in on UK variant, now the dominant strain in US The CDC says the UK variant has become the most dominant COVID strain in the United States. That strain, B.1.1.7, is also widely circulating in Florida. and last updated 2021-04-12 18:01:57-04 The CDC says the UK variant has become the most dominant COVID strain in the United States. That strain, B.1.1.7, is also widely circulating in Florida. "Based on our most recent estimates from CDC surveillance, the B.1.1.7 variant is now the most common lineage circulating in the United States," CDC director Rochelle Walensky said last week.