US President Donald Trump and the first lady Melania Trump have tested positive for Covid-19, the president said in a tweet.

The news came hours after Hope Hicks, a top and closest aide to Trump, was confirmed to have tested positive for Covid-19.

Hicks reportedly travelled with Trump on Air Force One during the first presidential debate which took place in Cleveland, Ohio.

"We will begin our quarantine and recovery process immediately,” Trump tweeted. "We will get through this TOGETHER!”

The development means the president could cancel in-person events in the coming weeks, possibly including the next debate against Democrat Joe Biden on October 15 in Miami. 

The development also comes as the Covid-19 infection rate in the UShas surpassed 7.3 million people, with more than 200,000 having succumbed to the virus.

Trump is 74 and that makes him vulnerable to the virus. According to health experts, elderly people are more susceptible to the virus than young ones.

The president’s positive test comes after several members of the White House became infected with the virus. 

National security adviser Robert O’Brien and Katie Miller, the vice president’s press secretary, previously tested positive and have since recovered. 

Trump has faced sharp criticism for his handling of the coronavirus pandemic. He has refused to wear a mask in public for a long time now. 

He has repeatedly predicted the virus would disappear and earlier this week said the country was "rounding the corner” on the pandemic. 

He has also expressed skepticism about the opinions of health experts in his administration, saying that in many cases he feels he knows better than them. 

The president also resumed campaign rallies, including indoor events even as health officials urged Americans not to gather in crowded indoor spaces. 

Mask-wearing is rare at his rallies. He has criticized Joe Biden, Democratic Party nominee, for wearing a mask, as recently as in Tuesday’s debate. 

"He could be speaking 200 feet away from it, and he shows up with the biggest mask I’ve ever seen,” Trump said.

Earlier this year, the president said he began taking the antimalarial drug hydroxychloroquine to prevent contracting the virus. It isn’t a proven treatment. 

If Trump's conditions were to worsen, he could temporarily transfer power to Vice President Mike Pence under the 25th amendment.