During the first presidential debate US President Donald Trump mocked Joe Biden for wearing masks in public.
On Tuesday the president said he wore masks "when needed" but said his opponent Biden wore masks unnecessarily when people were "200 feet away from him and he shows up with the biggest mask I've ever seen".
Since then, Trump and his wife Melania have tested positive for coronavirus after the president's close aide Hope Hicks became infected.
During the debate, moderator Chris Wallace asked Trump about his position on masks.
"President Trump, you have begun to increasingly question the effectiveness of masks as a disease preventer," Wallace said.
"And in fact, recently you have cited the issue of waiters touching their masks and touching plates. Are you questioning the efficacy of masks?"
"No, I think masks are okay," Trump replied. "You have to understand, if you look … I mean, I have a mask right here. I put a mask on when I think I need it.
"Tonight, as an example, everybody's had a test and you've had social distancing and all of the things that you have to, but I wear masks …"
"Just like your rally," Biden said.
" … when needed. When needed, I wear masks," Trump said.
Trump then continued: "I don't wear a mask like him. Every time you see him, he's got a mask. He could be speaking 200 feet away from him and he shows up with the biggest mask I've ever seen."
Biden responded, and started talking about reopening businesses.
"Well, masks make a big difference. His own head of the CDC said if we just wore masks between now, if everybody wore a mask and social distanced between now and January, we'd probably save up to 100,000 lives. It matters. It matters."
Trump responded, insisting he'd also been told "the opposite".
"And they've also said the opposite. They've also said …"
"No serious person has said the opposite. No serious person," Biden said.
Wallace, the moderator, then tried to interject but Trump continued, saying: "Dr Fauci. Dr Fauci said the opposite."
"He did not say the opposite," Biden said.
Dr Anthony Fauci is the head of the Institute for Allergies and Infectious Diseases and a member of the White House Coronavirus Task Force.
The US Centres for Disease Control and Prevention (CDC) has been urging all US citizens in a community setting to wear face masks to slow the spread of Covid-19 since July. The CDC's director, Dr Robert R Redfield, said face coverings are "one of the most powerful weapons" in stopping the spread of coronavirus.
"I want to ask you, we've got a little more than a minute left in this segment …" Wallace said, again trying to move away from a discussion about masks.
"He said very strongly, 'Masks are not good'. Then he changed his mind. He said, 'Masks are good'," Trump continued.
"I'm okay with masks. I'm not fighting masks."
Wallace then brought up the two candidates' different approaches to campaigning.
"President Trump, you're holding large rallies with crowds packed together, thousands of people," Wallace said.
"Outside," Trump said.
"Outside. Yes, sir. Agreed," Wallace said. "Vice President Biden, you are holding much smaller events with …"
"Because nobody will show up," Trump said. "Well, it's true. Nobody shows up to his rallies."
Trump defended holding larger rallies, saying "people want to hear what I have to say".
"I'm doing my job as a president, and I'll have 25, 35,000 people show up at airports. We use airports and hangers and we have a lot of people."
When asked if he was worried about the disease, Trump said, "Well, so far we have had no problem whatsoever. It's outside.
"That's a big difference according to the experts. We do them outside, we have tremendous crowds, as you see, and literally on 24 hours notice.
"And Joe does the circles and has three people someplace."
Biden fired back at this point, saying Trump had been concerned about being infected by his fans.
"By the way, did you see one of the last big rallies he had," Biden said. "A reporter came up to him to ask him a question, he said, 'No, no, no. Stand back, put on your mask, put on a mask. Have you been tested? I'm way far away from those other people'.
"That's what he said, 'I'm going to be okay'. He's not worried about you. He's not worried about the people out there."
Trump insisted there'd been no "negative effect" at various rallies, which he said had been attended by up to 35,000 and 40,000 people.
"He's been totally irresponsible the way in which he has handled the social distancing and people wearing masks, basically encouraged them not to," Biden said. "He's a fool on this."
"If you could get the crowds, you would have done the same thing," Trump said as a final shot.
"But you can't. Nobody cares."