The reminders come like most states begin the first phase of reopening the economies despite a growing nationwide death toll.
At least 78,794 Americans have died and more than 1,309,500 have been infected.
And last week brought another piece of disturbing news: New York state authorities believe that an inflammatory disease observed in dozens of young people – who killed two children and a teenager – may be linked to the virus.
But governors have begun to relax measures across the United States amid protests from residents and business owners demanding an end to sweeping orders to stay home. And as states struggle to find a way toward the new norm, several protests have taken shape across the country by residents who refused to put on face covers.
Public health experts have warned that the United States is not ready to begin reopening – citing lack of adequate testing and contact tracking efforts, among other reasons – and premature repeal of measures could mean a death toll that is twice as high as before predicted. But the effects of the loosening measures will not be visible for a while.
"It will take at least two to three weeks for us to see an increase in infections because it takes time for individuals to infect others and for them to show symptoms," said computer scientist Youyang Gu, whose coronavirus projection model is quoted by the CDC, told CNN.
Top health professionals exposed to viruses
Fauci is one of a handful of top authorities and health authorities who announced that they had come in contact with an infected person in the White House.
Dr. Stephen Hahn, Commissioner for Food and Drug Administration, will also quarantine after coming in contact with a person who tested positive for the virus, an FDA spokesman confirmed to CNN on Friday.
Officials did not identify the person to whom Hahn or Redfield were exposed. However, Katie Miller, the press secretary for Vice President Mike Pence, tested positive on Friday. She is known for often being in the White House coronavirus work board meetings.
An illness seen in children can be related to viruses
A teenager and two children under the age of eight died from an inflammatory disease observed in dozens of children in New York, state authorities said Saturday.
That disease may be linked to the virus, they said.
"We worked under the impression that young people were not affected by Covid-19," said Prime Minister Andrew Cuomo. "We're not so sure that's the fact anymore."
Researchers still do not know if coronavirus caused the syndrome. But this is under investigation, Cuomo said.
"We still have a lot to learn about this virus," he said.
State officials had previously warned that dozens of children in the state had been hospitalized with a condition doctors described as "pediatric multisystem inflammatory syndrome," and that it may be linked to coronavirus.
The children had fever and symptoms similar to toxic shock syndrome and Kawasaki disease, the state had said. Kawasaki disease causes inflammation of the walls of the blood vessels, including those that supply blood to the heart, which in rare cases can lead to fatal blood flow restrictions.
Many of the children tested positive for the virus or had antibodies, Cuomo said, but they did not necessarily have typical symptoms of coronavirus disease, such as respiratory problems.
CNN's Madeline Holcombe and Jason Hanna contributed to this report.