B.1.1.7, the Highly Infectious Coronavirus Variant, Could Soon Dominate the U.S. Prevention 2/9/2021 Korin Miller A highly infectious coronavirus variant that was first detected in the U.K. is now rapidly spreading in the U.S. The variant, B.1.1.7, has been detected in at least 34 states so far and is expected to continue circulating. A new preprint study estimates that cases of the variant are doubling in the U.S. every nine days, with an increased transmission rate of up to 45%.“Our study shows that the U.S. is on a similar trajectory as other countries where B.1.1.7 rapidly became the dominant SARS-CoV-2 variant, requiring immediate and decisive action,” the researchers wrote.