In other news, the United Kingdom's Chief Medical Officer, Chris Whitty, says there's very little chance we'll have widespread access to a vaccine for the coronavirus within the next calendar year.
“In the long run, the exit from this is going to be one of two things, ideally, one of which is a highly effective vaccine ... and/or highly effective drugs,” he told reporters.
“Until we have those - and the probability of having those any time in the next calendar year are incredibly small and I think we should be realistic about that - we’re going to have to rely on other social measures.”
Meanwhile, CDC Director Robert Redfield says the next outbreak of the virus, which he expects in the fall or winter, could be worse because it will coincide with flu season.
Finally, some infected people in Wuhan, China are still testing positive for the virus over two months after they recovered.
Chinese doctors in Wuhan, where the virus first emerged in December, say a growing number of cases in which people recover from the virus, but continue to test positive without showing symptoms, is one of their biggest challenges as the country moves into a new phase of its containment battle.
Those patients all tested negative for the virus at some point after recovering, but then tested positive again, some up to 70 days later, the doctors said. Many have done so over 50-60 days.
The prospect of people remaining positive for the virus, and therefore potentially infectious, is of international concern, as many countries seek to end lockdowns and resume economic activity as the spread of the virus slows. Currently, the globally recommended isolation period after exposure is 14 days.