https://www.siliconvalley.com/2021/12/20/covid-omicron-is-now-the-dominant-strain-of-coronavirus-in-the-u-s/

(CNN) — The Omicron Covid-19 variant is now the most dominant strain in the US, accounting for over 73% of new coronavirus cases less than three weeks after the first was reported, according to estimates posted Monday by the US Centers for Disease Control and Prevention.

It’s been just 20 days since the US detected its first case of Omicron.