Experts on the White House Covid-19 task force say the coronavirus outbreak is starting to level off across the US.
Dr Deborah Birx said there were good signs the outbreak was stabilising, but cautioned: "As encouraging as they are, we have not reached the peak."
President Donald Trump also said he expects the US to see a lower death toll than the initial predictions of 100,000 fatalities.
The US has over 475,000 confirmed cases and nearly 18,000 deaths so far.
Dr Anthony Fauci, US infectious diseases chief, concurred that the US is "starting to see the levelling off and coming down" of cases and deaths.
But he added that despite the "important advance", mitigation efforts such as social distancing should not be pulled back yet.
Dr Birx noted that the rate of increase appears to be stabilising in hard-hit regions like New York, New Jersey and the city of Chicago.
She added that the US mortality rate is "significantly less than many of the other countries, when you correct them for our population".
But she emphasised the nation had yet to see the peak of the outbreak. "We need to continue to do what we did yesterday, and the week before, and the week before that because that's what, in the end, is going to take us up across the peak and down the other side."
The Institute for Health Metrics and Evaluation in Washington state has predicted the nation's death count will peak on Friday and then begin declining.
On Friday, the governor of New York – the global epicentre of the virus – said the latest data shows that the state is successfully "flattening the curve".
Despite 777 new deaths in New York on Thursday, the number of patients requiring intensive care treatment in hospital had gone down for the first time since the crisis began.
"Even though it's a grind, even though it's difficult, we have to stay with it," Governor Andrew Cuomo said, cautioning that it was still too early to relax social distancing measures.
The danger appears to be highest for America's minority communities, which have been disproportionately affected by Covid-19.
Dr Jerome Adams, the US Surgeon General, said that trend was "alarming, but not surprising" given that minorities in the US generally have more chronic health conditions such as asthma, hypertension and diabetes.
"As a matter of fact, I have been carrying an inhaler in my pocket for 40 years out of fear of having a fatal asthma attack," continues Dr Adams, who is African-American.
In Friday's White House briefing, Mr Trump said he had seen the drone images of coffins being stacked in a mass grave on New York's Hart Island.