Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, is warning against attempts to place concrete time limits on the coronavirus pandemic, telling CNN’s Chris Cuomo “the virus makes the timeline.”

Asked Wednesday night about varying projections from different states and jurisdictions for how long social distancing measures and shutdowns will stay in place, Cuomo said “it seems like the timeline is getting extended farther out, not that things are going better than expected anywhere.”

“You’ve got to be realistic, and you’ve got to understand that you don’t make the timeline, the virus makes the timeline,” Fauci replied.

“So you’ve got to respond to what you see happen, and if you keep seeing this acceleration, it doesn’t matter what you say, one week, two weeks, three weeks, you’ve got to go with what the situation on the ground is,” he added.

“You don’t make the timeline. The virus makes the timeline,” says Dr. Anthony Fauci on when coronavirus restrictions could be lifted. “…You have got to go with what the situation on the ground is… you need the data.” https://t.co/L2SlTmOJ6Z pic.twitter.com/jMem16dOdM

— Cuomo Prime Time (@CuomoPrimeTime) March 26, 2020

Fauci said that, in some cases, projections of months may refer to how long it takes for the infection curve to fully descend, whereas flattening may begin “in a relatively shorter period of time.”

He added, however, that “you can’t make an arbitrary decision until you see what you’re dealing with.”

President Trump has said he wants to reopen the economy by Easter, sparking pushback from state officials and health experts.

Deaths in the U.S. from the novel coronavirus surpassed 1,000 on Thursday, according to data compiled by Johns Hopkins University, while domestic cases exceeded 69,000.