President Donald Trump said he will not participate in the next debate with Democratic nominee Joe Biden if it will be conducted virtually as a precaution against the spread of the coronavirus.

"No I'm not going to waste my time on a virtual debate," Trump said in a telephone interview with Fox Business Thursday. "That's not what debating's about."

The Commission on Presidential Debates announced earlier that the October 15 forum in Miami, the second of three presidential debates, will be a town hall with the participants appearing from remote locations.

The decision was made "in order to protect the health and safety of all involved," the commission said in a statement. It comes after Trump was hospitalised with COVID-19 over the weekend and the White House reported that a dozen staffers have become infected with the virus, which has killed more than 210,000 people in the US.

The Biden and Trump campaigns didn't immediately respond to requests for comment.

The president's doctor has said he is feeling better but has refused to release key details since Monday, such as Trump's specific vital signs, when he last tested negative, when he actually fell ill, and whether he's still receiving a steroid, dexamethasone.

The virus has circulated widely throughout the White House. Aside from Trump and the first lady, aides Hope Hicks, Nick Luna, Stephen Miller and Kayleigh McEnany have all tested positive, as has campaign manager Bill Stepien and former New Jersey Governor Chris Christie, who helped with debate prep.

Trump is pushing to return to normal, having gone to the Oval Office on Wednesday, despite still being in the active phase of the virus. The campaigns had haggled over rule changes after the first debate, which was marked by a series of interruptions from Trump in particular. The campaign has said that Trump "intends to be ready to debate" by October 15, and had opposed rule changes, such as a mute button that would allow moderators to cut off the microphone of a candidate.