"Our prayers are with them," Tedros said at the start of the media briefing, after U.S. administration officials said Trump is experiencing mild symptoms after testing positive for the deadly coronavirus.
The couple went into quarantine, the White House said.
WHO's emergency expert Mike Ryan called COVID-19 a 'nasty virus' that 'can cause severe disease particularly in older individuals with underlying conditions."
Trump has played down the threat of the coronavirus pandemic from the outset despite repeated warnings from the WHO about the severity of the pandemic.
Trump has savaged the WHO for its handling of the pandemic and accused it of being too close to China, where the virus emerged.
The U.S., formerly top donor of the Geneva-based body, has said it plans to withdraw and cut off funding.
TEDROS ADHANOM GHEBREYESUS: Overnight, we heard that the President of the United States of America, Donald Trump, and First Lady Melania Trump tested positive for COVID-19. I want to start today by wishing them both a full and swift recovery. Our prayers are with them.
MIKE RYAN: This is a nasty virus. And this virus can cause severe disease, particularly in older individuals with underlying conditions. So we wish the president and his partner well in this process and anyone else who is affected within that-- within that cluster.
What we will reiterate is that each and every individual and each and every citizen should be guided by the national guidance in their country. And that's the combination of different measures that reduce risk and we know these reduce risk-- washing your hands, staying a safe distance from other individuals, avoiding crowded spaces, wearing a mask, both to protect others and yourself in situations where you can't physically distance or where there is a risk. And doing all of that to protect yourself and others is the best way to protect society. Our advice--