"It’s very sobering to see the increase in deaths and we predicted over the weekend that this would really be a bad week and it is", National Institute for Allergy and Infectious Diseases (NIAID) Director Anthony Fauci said in an interview.
"It’s going to be a bad week for deaths, but driving that and ahead of that is the fact that we’re going to start to see the beginning of a turnaround, so we need to keep pushing on the mitigation strategy because there’s no doubt that that’s having a positive impact on the dynamics of the outbreak", he added.
More than 1,800 people died in the 24-hour period on Tuesday, the highest single day so far, according to official and media reports.
But Fauci cited the drop in hospital admissions, new cases and patients requiring ventilators - reported by the state of New York in recent days - as evidence social distancing and other mitigation are beginning to slow the pandemic.
Death rates typically lag the number of new cases by a "couple of weeks", meaning that as the nation moves beyond this week, "we should start to see the beginnings of a turnaround", Fauci said.
About 4,000 COVID-19 patients died so far in New York, the epicentre of the US outbreak, in an epidemic that has sickened about 400,000 people throughout the United States.