The United States reported at least 1.13 million new coronavirus infections on Monday, according to a Reuters tally, the highest daily total of any country in the world.
The previous record was 1.03 million cases on January 3. A large number of cases are reported each Monday are due to many states not reporting over the weekend. The seven-day average for new cases has tripled in two weeks to more than 700,000 new infections a day.
Not all states had yet reported on Monday and the final figure is likely to be even higher.
The record in new cases came the same day as the nation saw the number of hospitalised COVID-19 patients also hit an all-time high, having doubled in three weeks, according to a Reuters tally.
There were more than 135,500 people hospitalised with COVID, surpassing the record of 132,051 set in January last year.
While the Omicron variant is potentially less severe, health officials have warned that the sheer number of infections could strain hospital systems, some of which have already suspended elective procedures as they struggle to handle the increase in patients and staff shortages.
The surge in cases has disrupted schools, which are struggling with absences of staff, teachers and bus drivers. Chicago cancelled classes for a fourth day as the district and teachers failed to agree on how to deal with increased infections.
New York City suspended service on three subway lines due to a large number of workers out sick, according to its Twitter account. Companies' plans for workers to return to office have also been derailed.
Deaths are averaging 1,700 per day, up from about 1,400 in recent days but within levels seen earlier this winter.