Americans must resist the impulse to ease social-separation measures at the first glimpse of progress now being seen in the coronavirus battle, state government and public health leaders warned on Thursday, as the U.S. death toll surpassed 16,500.

Calls for heightened vigilance, countering talk from the Trump administration of reopening the economy next month, came as new evidence emerged that stay-at-home restrictions were working to flatten the arc of infections in New York state, the U.S. epicenter of the pandemic.

The number of newly hospitalized patients in New York dropped for a second day, to 200. Gov. Andrew Cuomo said it was a sign that social distancing was succeeding, even though the number of coronavirus-related deaths in the state rose by 799 on Wednesday, a record high for a third day.