With three people in the White House -- President Trump, first lady Melania Trump, and top aide Hope Hicks -- now testing positive for coronavirus, questions are arising as to how many people within the administration may have been exposed to the virus.
The administration needs to "trace their contacts and start quarantining people who have been in close contact with somebody," said CNN's Chief Medical Correspondent Sanjay Gupta. "And that's going to be a very important policy, here, within the West Wing."
Figuring out who has been exposed includes many criteria, he added: how close were they in contact? How long did the contact last?
Joe Biden potentially exposed: Former Vice President Joe Biden, the Democratic presidential nominee, "may have been far enough away on that stage" on Tuesday night during the presidential debate with Trump, said Sanjay.
"And I know that they came in from different areas, probably did not spend time close together. But he is going to need to be tested as well. All the campaign staffers. It's going to be critical."
Even if they weren't in close contact and stood far apart from each other, "we are dealing with the leaders of the country, here," he said.
The timeline of exposure and infection: Infection can also take a while to set in after the moment of exposure, he added.
"People will say, well, I tested negative the next day, after the exposure. Therefore, I am good to go. That is not the case. You could have exposure today, test negative tomorrow, the next day, and so forth for several days. And then, suddenly, test positive."
Hear more from Dr. Gupta: