Coronavirus deaths are rising in American states as a winter surge pushes the toll towards 400,000 amid warnings that a new, highly contagious variant is taking hold.
As Americans observed a national holiday Monday, New York Governor Andrew Cuomo pleaded with federal authorities to stop travel from countries where new variants are spreading.
The mutant strains were first detected in Britain, South Africa and Brazil.
“Stop those people from coming here," Mr Cuomo said. "Why are you allowing people to fly into this country and then it’s too late?”
The US government has already curbed travel from some places where the new variants are spreading, such as Britain and Brazil.
It recently announced that it would require proof of a negative Covid-19 test for anyone flying into the country.
But the new variant from Britain is already spreading in the US, and the Centres for Disease Control and Protection warns that it will probably be the dominant version in the country by March.
The CDC said the variant was about 50 per cent more contagious than the virus that was causing most cases in the US.
While the variant does not cause more severe illness, it can cause more hospital admissions and deaths because it spreads more easily.
In Britain, it has aggravated a severe outbreak that has swamped hospitals, and it has been blamed for sharp leaps in cases in some other European countries.
Many US states are already under tremendous strain.
The seven-day rolling average of daily deaths is rising in 30 states and the District of Columbia, and on Monday the US death toll passed 398,000, Johns Hopkins University says – by far the highest recorded death toll of any country.
Ellie Murray, an assistant professor of epidemiology at the Boston University School of Public Health, said cases have proliferated in part because of gatherings for Christmas and New Year.
That compounded previous surges from Thanksgiving and the return of pupils to schools and universities in the autumn.
The pace of any further spread will depend on whether those who did gather with family and friends went into isolation afterwards or returned to school or work in person, Ms Murray said.
As the cases rise, a vast effort is under way to have Americans vaccinated, in what Mr Cuomo called “a footrace” between the vaccination rate and the infection rate.
But the campaign is off to an uneven start. The latest federal data shows about 31.2 million doses of vaccine have been distributed but only about 10.6 million people have received at least one dose.
In some cases, vaccine supplies do not meet demand. More than 172,000 people in Missouri’s St Louis County have registered for the vaccine, but the the local health department so far has only received 975 doses, county executive Sam Page said.
In California, the most populous state, counties are pleading for more vaccine as the state tries to reduce a high rate of infection that has led to record numbers of hospital admissions and deaths.
Although the state last week said anyone aged 65 and older could start receiving the vaccine, Los Angeles County and some others say they do not have enough to immunise so many people.
They are concentrating on protecting healthcare workers and the most vulnerable elderly in care homes first.
On Monday, the superintendent of the Los Angeles Unified School District sent a letter asking for state and county authorisation to provide vaccinations at schools for staff, local community members, and for pupils once a vaccine for children was approved.
The death rate from Covid-19 in Los Angeles County, a centre of the US pandemic, works out to about one person every six minutes.
On Sunday, the South Coast Air Quality Management District suspended some pollution-control limits on the number of cremations for at least 10 days to deal with a backlog of bodies at hospitals and funeral homes.
In other areas of the country, officials are trying to ensure people take the vaccine when it is offered amid concerns that many are hesitant.
Maryland Governor Larry Hogan, in an event streamed live on Martin Luther King Jr Day, received a shot and urged other Marylanders to do likewise.
“We’re all looking forward to the day we can take off and throw away our masks,” Mr Hogan said.
“The only way we are going to return to a sense of normalcy is by these Covid-19 vaccines.”
