In a new MMWR, CDC’s expanded genomic surveillance shows that the B.1.1.7 variant grew from less than 1% of U.S. #COVID19 cases in January 2021 to about 66% by April 24. CDC continues to monitor variants to help end the pandemic. Learn more: https://t.co/1Q6UvSXeNp. https://t.co/dFaaVQjEFS