The prospects of an imminent reopening of the US for travel and cruises have been dampened as the head of the country’s public health agency warned Americans to “limit” travel.

Dr Rochelle Walensky, director of the US Centres for Disease Control and Prevention (CDC), said the US faces “impending doom” amid rising Covid-19 cases and hospital admissions.

She was speaking at a White House Covid briefing when she said she was going to go “off script”.

“I’m going to reflect on the reoccurring feeling I have of impending doom,” Walensky said, adding “we have so much reason for hope, but right now I’m scared”.

She said: “I would just sort of reiterate the recommendations from [the] CDC, saying please limit travel to essential travel for the time being.”

New Covid cases have reached around 60,000 a day in the past week, a rise of around 7%, according to the CDC.

Walensky said she did not want the US to face another spike in cases and deaths as has happened in many European countries.

Her comments came despite president Joe Biden promising that 90% of American adults would be able to receive a vaccine by mid-April. All will be able to register for a dose by May 1.

More than one in five adults and nearly all Americans aged over-65 are fully vaccinated.

However, Biden called for state governors to re-introduce laws that require people to wear masks.

“If we let our guard down now, we can see the virus getting worse, not better,” he said.