Jennifer Nuzzo

Frederic J. Brown / AFP VIA Getty Images

The Centers for Disease Control and Prevention has revised its guidelines for people who may have been exposed to the coronavirus. Now, instead of the standard 14-day quarantine it has been recommending, the CDC says that potential exposure warrants a quarantine of 10 or seven days, depending on one's test results and symptoms.

Federal health officials are likely to shorten their recommendation for how long people should quarantine to reduce the risk of spreading the coronavirus from the current 14 days to as few as seven.

Updated 1:20 p.m. ET

The spread of the coronavirus inside the White House is a stark reminder of the danger of relying on testing to prevent outbreaks, experts say.

"I think the takeaway is clear: Testing alone is not a sufficient strategy to prevent spread of the virus," says Daniel Green, an assistant professor of pathology and cell biology at Columbia University.

"A negative test does not give free license to forgo all other safety measures," Green says.