The Biden administration has announced a new set of measures to keep schools open, including increasing access to Covid-19 tests, as the highly contagious Omicron variant spreads rapidly through the United States, Reuters reports.

The United States reported 1.35 million new coronavirus infections on Monday, according to a Reuters tally, the highest daily total for any country in the world.

Omicron was estimated to account for 98.3 per cent of total new coronavirus cases circulating in the country as of Jan. 8, the CDC said on Tuesday. The White House and top health officials on Tuesday defended the government's response to the surge in cases and hospitalisations.