The US recorded a record number of hospitalisations due to Covid-19, the Biden administration said, as daily infections soared to more than 1.35m. Nonetheless, politics dominated a Senate hearing on the pandemic on Tuesday, as Republicans attempted to use the disease for political gain.

Rand Paul of Kentucky clashed once again with Anthony Fauci, Joe Biden’s chief medical adviser.

“In usual fashion, Senator, you are distorting everything about me,” Fauci said. “You keep coming back to personal attacks on me that have absolutely no relevance.”

Paul, who has repeatedly used public health hearings for political grandstanding and launching personal attacks on Fauci, variously accused the immunologist of working to smear scientists and being responsible for school closures, while reiterating rightwing theories about the origin of Covid-19.

Fauci has been subjected to death threats and said his family had been harassed “because people are lying about me”.

He held up a printout of a page on Paul’s campaign website, which had the banner “Fire Dr Fauci” next to an invitation to donate to Paul’s re-election effort.

“You are making a catastrophic epidemic for your political gain,” Fauci said.

He also described the arrest in Iowa in December of a man who police said planned to kill Fauci and other powerful figures and was carrying an assault rifle.

“What happens when [Paul] gets out and accuses me of things that are completely untrue,” Fauci said, “is that it kindles the crazies out there and I have threats upon my life, harassment of my family and my children with obscene phone calls because people are lying about me.”

There were 145,982 people hospitalised with coronavirus in the US on Monday, according to data from the Department of Health and Human Services. Reuters reported that the previous high was 132,051, set in January 2021.

According to Reuters there were 1.35m new Covid infections on Monday, also a record. Measures vary and observers point out that many home tests are not officially logged. But NBC News reported at least 1,343,167 new infections.

The highly contagious Omicron variant has seen hospitalisations double in three weeks. The seven-day average for new cases has tripled in two weeks to more than 700,000 a day.

Large numbers of Covid cases tend to be reported on Mondays due to many states not reporting over the weekend, but the 1.35m total reported this week comfortably outstripped the previous record of 1.03m, recorded on Monday 3 January.

Delaware, Illinois, Maryland, Missouri, Ohio, Pennsylvania, Puerto Rico, the US Virgin Islands, Vermont, Virginia, Washington DC and Wisconsin have reported record levels of cases recently.

Only seven states have not set records for cases in 2022: Arizona, Idaho, Maine, Montana, North Dakota, Ohio and Wyoming, Reuters said.

At the Senate hearing, Fauci was asked for an update on the effect of the virus on vaccinated people compared with unvaccinated people. He reiterated that getting vaccinated was the best way to avoid serious illness.

Fauci said unvaccinated people were 10 times more likely to test positive for Covid-19, 17 times more likely to be hospitalised and 20 times more likely to die.

As cases and hospitalisations soar, health authorities around the US are increasingly taking the once unthinkable step of allowing nurses and other workers infected with Covid to stay on the job if they have mild symptoms or none at all, the Associated Press reported.

The move is a reaction to the severe hospital staffing shortages and crushing caseloads that Omicron is causing.

California health authorities announced over the weekend that hospital staff members who test positive but are symptom-free can continue working. Some hospitals in Rhode Island and Arizona have given employees similar guidelines.

In December, the CDC said healthcare workers who have no symptoms can return to work after seven days with a negative test but that the isolation time “can be cut further if there are staffing shortages”.

In Tuesday’s hearing, Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), clarified federal guidance. She said fully vaccinated people exposed to the virus do not need to stay at home unless they develop symptoms, but should wear a mask, get tested and avoid travel until after day 10.

The threat of Omicron and number of new cases has led to an increased demand for tests, with long lines and shortages around the country.

On Monday the White House said insurance companies will be required to cover eight over-the-counter at-home tests per person each month starting on 15 January.

In December, Joe Biden said half a billion at home tests would be sent free to Americans, beginning in January.