The United States crossed 50 million coronavirus cases on Sunday, according to Reuters tally, as the Delta variant continues to threaten Americans and the newly discovered Omicron variant spreads.

After about two months of declining infections, the United States has reported daily increases for the past two weeks, driven by the more easily transmitted Delta variant.

The number of hospitalized Covid patients is rising as well, up 20 per cent since the Thanksgiving holiday at the end of November.