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.