New York recorded its single greatest one-day jump in deaths from COVID-19, the respiratory disease caused by the coronavirus, but the state's governor pointed to signs that the state may be reaching a plateau in its wrenching efforts to limit the damage caused by the pandemic.

The death count for April 6 of 731 marked an increase from the previous day's 599 new deaths, Gov. Andrew Cuomo told a daily briefing on the coronavirus. The overall total of casualties in the state is now 5,489 people.

But Cuomo stressed that deaths were often a lagging indicator of patients who have been battling the illness for days or weeks. While new hospitalizations in the state crept up from the previous day's total, at 654, there were just 89 new admissions to intensive care attributable to the coronavirus.

The ICU figure was the state's lowest total in two weeks and a sign for optimism as beleaguered hospitals, particularly in New York City and surrounding areas, have confronted escalating demands for scarce ventilators for patients and personal protective equipment for medical staff.

But the toll is increasingly grim nationwide. According to the resource centre at Johns Hopkins University in Maryland, over 11,850 people have died in the United States, a total that has skyrocketed since late March. There are over 378,000 confirmed cases, though experts consider the number understated due to a lack of testing capacity in many states.

The resource centre has recorded 3,485 deaths in New York City alone.

The U.S. national Centers for Disease Control and Prevention reported a whopping increase of 3,154 American deaths on Monday, compared to its previous daily report. The CDC has put the country's death toll at 12,064 as of Monday at 4 p.m. ET.

A person is tested for COVID-19 in the parking lot at Henry Ford Hospital in Detroit on Wednesday. Michigan is among the states where African Americans have been particularly hard hit by the pandemic. (Jeff Kowalsky/AFP via Getty Images)

The figures were updated after senior U.S. health officials from the federal government said Tuesday that they believe mitigation efforts are working nationwide, and that they now believe the coronavirus outbreak may kill fewer Americans than some recent projections.

U.S. Surgeon General Jerome Adams on Tuesday said he concurred with the director of the CDC that some research models have projected death totals that may prove too high, though neither would offer an alternate estimate.

The White House coronavirus task force projected a death toll of 100,000 to 240,000 a week ago, saying containing deaths to that range was possible if strict physical distancing measures were respected, implying it could go even higher.

Adams on Tuesday told ABC's Good Morning America that he was encouraged by recent data showing a possible "flattening" of the outbreak in some areas, referring to the shape of the curve when deaths are shown on a graph.

Asked if he believed the death toll would come in below the dire White House task force projection, Adams said, "That's absolutely my expectation."

First responders carry a patient on a stretcher from a house on Tuesday in the Queens borough of New York City. Hospitals in New York City, which have been especially hard hit by the coronavirus, are facing shortages of beds and ventilators but saw fewer intensive care admissions due to COVID-19 on Monday. (Kena Betancur/Getty Images)

A research model from the University of Washington — one of several cited by leading health authorities — forecasts 81,766 U.S. coronavirus fatalities by Aug. 4, down about 12,000 from a weekend projection.

President Donald Trump has said any death toll less than 100,000 should be considered a successful response from his administration.

Racial disparities 'take your breath away'

Also tempering the cautiously optimistic tenor from Cuomo and federal officials, early data from U.S. states shows African Americans have been more likely to die from COVID-19, highlighting longstanding disparities in health and inequalities in access to medical care, experts said.

Data from Chicago officials on Monday showed that black residents make up 52 per cent of coronavirus infections and 72 per cent of deaths from COVID-19.

"Those numbers take your breath away. This is a call to action moment for all of us," Chicago Mayor Lori Lightfoot said.

A woman wears a mask to try and prevent the spread of COVID-19 at a supermarket in Washington, D.C., on Tuesday. (Saul Loeb/AFP via Getty Images)

On Tuesday, Lightfoot told a news briefing that her city has gone from coronavirus cases doubling every one to two days to doubling every nine to 10 days because residents have complied with the state's stay-at-home order. The city has documented 5,043 cases and 118 deaths.

"It's obviously progress," Lightfoot said. "But we are not near the peak so I don't want to raise false expectations that it's coming sometime soon based on the modelling that we have seen."

Louisiana and Michigan have also reported rates of death from coronavirus among African Americans far greater than their representation in overall state population.

Adams, who is black, told the CBS program, This Morning: "We know that blacks are more likely to have diabetes, heart disease, lung disease. And I have shared myself, personally, that I have high blood pressure."

Governors of hard-hit states have criticized the government in Washington for what they see as a lack of centralized direction, a trend that continued Tuesday. New Jersey Gov. Phil Murphy called for a "massive post-mortem" on the response both in his state and federally, while describing an "unfathomable" death toll of over 1,230 state residents.

Murphy on Tuesday thanked California, which will be sending 100 ventilators. About 94 cer cent of the ICU admissions in his state related to COVID-19 require the use of ventilators, he said.

"From the bottom of our hearts, thank you. We will repay the favour when California needs it," said Murphy.

We currently have 7,017 hospitalizations, including <a href="https://twitter.com/hashtag/COVID19?src=hash&ref_src=twsrc%5Etfw">#COVID19</a> positive patients and persons under investigations.<br><br>1,651 individuals are in critical care. 94% of those individuals – 1,540 individuals – are on ventilators. —@GovMurphy

Trump, who has promoted the use of hydroxychloroquine in treating COVID-19, attacked the inspector general for the Department of Health and Human Services on Tuesday, accusing her in a tweet of having produced a "fake dossier" on American hospitals suffering shortages of personal protective equipment on the front-lines of the outbreak. Trump did not provide any reason for questioning the report on those shortages, which was based on a survey of over 300 hospitals in late March.

On the legislative front, the White House was preparing to ask Congress for an additional round of emergency loans to help small businesses hobbled by the pandemic, and Senate Majority Leader Mitch McConnell said he hoped for approval this week.

"It is quickly becoming clear that Congress will need to provide more funding or this crucial program may run dry," McConnell, a Republican, said in a statement. He added that he would work with Treasury Secretary Steven Mnuchin and Senate Democratic Leader Chuck Schumer on the initiative with the goal of winning Senate approval on Thursday.

It's not clear if Democrats will agree on the timeline. In a CNN interview on Tuesday, House Speaker Nancy Pelosi also criticized Trump for an apparent move to replace the chair of a board that will oversee the $2.2-trillion US legislative package enacted last month to help provide relief for businesses and individuals.