"I've no doubt that he will, he'll make a very strong recovery," Johnson told UK media.
"He's a naturally obviously very resilient character and I'm sure he'll come through it very well."
Trump has played down the threat of the coronavirus pandemic from the outset, even as the disease has killed more than 200,000 Americans and hammered the U.S. economy.
BORIS JOHNSON: I rang the family last night and [? I didn't ?] talk to the president. And I think obviously everybody's wishing him and Melania the very best and hoping that they recover speedily. And I've no doubt that he will-- he'll make a very strong recovery.
Well, I think that he will be doing exactly what the doctors tell him to do. And I'm sure he'll be having the best care he could possibly get. And, you know, he's a naturally obviously very resilient character. And I'm sure he'll come through it very well.