WASHINGTON - The White House said that Mr. Robert O’Brien “has mild symptoms” and is working remotely from “a secure location off site.”

He is the most senior White House official known to contract the virus.

In the US, there are now 61,795 new cases to hit a total of 4,225,687.

Over 148,000 people have died from the virus.

Public skepticism toward vaccines is something officials will need to overcome once a coronavirus vaccine is ready for the public, Dr. Anthony Fauci told CNN

Fauci, director of the National Institute of Allergy and Infectious Diseases, which is working with Moderna on a potential vaccine, said there will need to be a campaign of community engagement and outreach.

"If we get a widespread uptake of vaccine, we can put an end to the pandemic and we can create a veil of immunity that would prevent the infection coming back," he told CNN's Wolf Blitzer.

"You have to do it by extending yourself to the community, not by a dictum from Washington."

The first Phase 3 clinical trial of a coronavirus vaccine in the US, developed by Moderna and the National Institute of Allergy and Infectious Diseases, began Monday. Fauci called it "crunch time" for vaccine development, and said he's "cautiously optimistic" about the progress.

The Moderna vaccine is one of 25 in clinical trials around the world, according to the World Health Organization. Pfizer and BioNTech also announced Monday that they have begun a Phase 2/3 study of a coronavirus vaccine.