US President Donald Trump has warned that as many as 100,000 people could die of coronavirus in the US.
Speaking at a two-hour virtual "town hall", Mr Trump also denied that his administration had acted too slowly.
More than 67,000 people have already died with Covid-19 in the US.
But Mr Trump expressed optimism about the development of a vaccine, suggesting one could be ready by the end of this year - although experts believe it will take 12 to 18 months.
"I think we're going to have a vaccine by the end of the year," he told Fox News. "The doctors would say, well you shouldn't say that. I'll say what I think... I think we'll a vaccine sooner rather than later."
Among the experts to disagree with this optimistic estimate are Dr Anthony Fauci, America's top infectious disease expert, and England's Chief Medical Officer, Chris Whitty.