The Surgeon General has warned Americans to prepare for "our hardest and saddest week" as the US braces for a spike in coronavirus-related deaths.

Jerome Adams told Fox News on Sunday that "this is going to be our Pearl Harbour moment, our 9/11 moment, only it's not going to be localised — it's going to be happening all over the country."

The US is entering a crucial two-week period to combat the virus, with nearly comprehensive statewide stay-at-home orders across the US and surges in hospitalisations and patients requiring ventilator support following Covid-19 infection.

By Sunday, eight states have not issued statewide shelter-in-place measures, and a handful of states don't have any quarantine measures on the state or local levels, creating a patchwork response to combat the spread of the virus while some areas have issued more stringent "social distancing" efforts.

Dr Anthony Fauci, who is leading the White House response to the outbreak, said this week that he "doesn't understand" why there isn't a national stay-at-home order, or at least why all 50 states aren't issuing consistent orders simultaneously, absent a federal mandate.

Surgeon General Adams pleaded with governors to "give us what you can" if not a month — or longer — of stay-at-home measures.

He said: "Give us a week. Give us whatever you can to stay at home in this particularly tough time when we're going to be hitting our peak in the next seven to 10 days."

By 5 April, the nationwide death toll from the virus had reached at least 9,132, according to Johns Hopkins University. There have been than 320,000 confirmed cases in the US.

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Donald Trump has warned that "there will be a lot of death" in coming days and weeks.

During a White House briefing on Saturday, he said: "This will be probably the toughest week between this week and next week, and there will be a lot of death, unfortunately."

Asked why the president — who has declared himself a "wartime" president against the "invisible enemy" that has sickened thousands of Americans — has not declared a national stay-at-home order, the surgeon general said that "governors are intensively protective of their right, and rightly so, to be able to decide what's best" for their respective states.

Fox host Chris Wallace said: [Franklin Delano Roosevelt] didn't say, 'Well, it's up to each state to decide what to do.' He mobilised the nation. ... The coronavirus doesn't recognise the state's rights. Does the federal analogy really work here?"