Stay-at-home orders intended to curb the spread of the coronavirus could end up causing "irreparable damage" if imposed for too long, White House health advisor Dr. Anthony Fauci told CNBC on Friday.
"I don't want people to think that any of us feel that staying locked down for a prolonged period of time is the way to go," Fauci said during an interview with CNBC's Meg Tirrell on "Halftime Report."
He said the U.S. had to institute severe measures because Covid-19 cases were exploding then. "But now is the time, depending upon where you are and what your situation is, to begin to seriously look at reopening the economy, reopening the country to try to get back to some degree of normal."
However, Fauci also cautioned states against reducing social distancing measures too quickly, adding they must take "very significant precautions."
"In general, I think most of the country is doing it in a prudent way," he said. "There are obviously some situations where people might be jumping over that. I just say please proceed with caution if you're going to do that."
Fauci has been criticized in recent days by Republicans, including U.S. lawmakers Rand Paul and Andy Biggs, for making comments appearing to advocate for keeping some businesses closed longer.
Just last week, Fauci, director of the National Institute of Allergy and Infectious Diseases, warned members of Congress that the United States could face even more "suffering and death" from the coronavirus if some states rush to reopen businesses too early.
It could also hinder states "on the road to try to get back to an economic recovery," he testified at a hearing before the Senate Committee on Health, Education, Labor and Pensions on May 12. "It would almost turn the clock back rather than going forward. That is my major concern."
The virus, which emerged in Wuhan, China, less than five months ago, has infected more than 1.5 million people in the United States, according to data compiled by Johns Hopkins University. States have started the process of reopening their economies after being shut down for weeks.
In a separate interview with NPR earlier in the day, Fauci said it was "conceivable" that the U.S. could begin to roll out a coronavirus vaccine by December.
He told CNBC that biotech firm Moderna's vaccine data, released earlier this week, was very encouraging.
Moderna has been fast-tracking work with the National Institutes of Health to develop a vaccine.
On Monday, the company released data from its phase one human trial on its potential vaccine, showing all 45 patients enrolled produced binding antibodies seen at similar levels of people who have recovered from the virus.
The vaccine produced neutralizing antibodies, which researchers believe are important to protect against the virus, for eight of the patients whose data was available so far. Data on neutralizing antibodies for the remaining patients is expected to come out later.
"We still have a long way to go obviously," Fauci said Friday. "There are so many things that need to be done. We're going to go quickly into a phase three trial probably in the beginning of the summer, sometime in July."
Correction: White House health advisor Dr. Anthony Fauci spoke to CNBC on Friday. An earlier version misstated the day.