Columbia University

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.

For nearly 20 years, a Columbia University gynecologist in New York City sexually abused dozens of female patients, including minors, according to a federal indictment unsealed Wednesday.

Robert Hadden, 62, was arrested that morning in connection with sexual abuse that took place from 1993 to 2012, including acts against a young girl whom Hadden had delivered at birth, court documents say.

Audrey Strauss, the Acting United States Attorney for the Southern District of New York, described him as a "predator in a white coat"

Dr. Anthony Fauci expressed "cautious optimism" Friday about the initial results from a coronavirus vaccine trial — which were widely celebrated this week — and said it remains "conceivable" that a vaccine for the deadly pathogen could be available by the end of the year.

Updated at 12:10 p.m. ET

The U.S. could have prevented roughly 36,000 deaths from COVID-19 if broad social distancing measures had been put in place just one week earlier in March, according to an analysis from Columbia University.

Underlining the importance of aggressively responding to the coronavirus, the study found the U.S. could have avoided at least 700,000 fewer infections if actions that began on March 15 had actually started on March 8.