Omicron BA.2 sub-variant was estimated to account for 85.9% of the coronavirus variants in the US, the national public health agency notified on Tuesday.
The COVID-19 surge in Asia and Europe has raised concerns that another wave could follow in the country, but health experts believe it is unlikely.
As per the official data, the Northeast, including New Jersey, New York and Massachusetts, is the hardest-hit, with Omicron BA.2 now accounting for more than 90% of the cases.
Philadelphia, a city in the northeastern state of Pennsylvania, will reimpose its indoor mask mandate from April 18, as a response to a fresh wave of cases.