Joe Biden is “feeling well” and “doing just fine” after testing positive for Covid, the White House coronavirus response coordinator said.

Appearing on CBS’s Face the Nation, Ashish Jha said: “So it is the BA.5 variant, which is about 80% of infections. But thank goodness, our vaccines and therapeutics work well against it, which is why I think the president’s doing well.

“I checked in with his team late last night. He was feeling well. He had a good day yesterday. He’s got a viral syndrome, an upper respiratory infection … and he’s doing just fine.”

The White House later released a letter in which Biden’s physician, Kevin O’Connor, said the president’s “predominant symptom now is a sore throat”.

O’Connor also said Biden had completed a third full day of treatment with Paxlovid, which would continue and was “experiencing no shortness of breath at all”.

Biden’s positive test was announced on Thursday. At 79, the president is the oldest ever inaugurated. He is also, as he said, double-vaccinated and double-boosted and has access to the best possible care.

On Sunday the transportation secretary, Pete Buttigieg, told CNN’s State of the Union he knew Biden was still working “because on Thursday I got a call from the White House about something on transportation that he had asked me to follow up on”.

Buttigieg also wished Biden “a speedy path back to 100%”.

Jha was asked if the White House “will continue to make disclosures if [Biden] has long-term symptoms from this infection”.

“Absolutely,” he said. “You know, we think it’s really important for the American people to know how well the president’s doing, which is why we have been so transparent, giving updates several times a day, having people hear from me directly, hear directly from his physician.

“And obviously if he has persistent symptoms, if any of them interfere with his ability to carry out his duties, we will disclose that early and often.

“But I suspect this is going to be a course of Covid that we’ve seen in many Americans who have been fully vaccinated, double-boosted, getting treated with those tools in hand. You know, the president has been doing well, and we’re gonna expect that he’s going to continue to do so.”

Jha also suggested cities seeing high case rates, including New York, Phoenix and Miami, might consider re-instituting indoor mask mandates.

“Masks work, right? They clearly slow down transmission. So in areas of high transmission, I think it’s very prudent for people to be wearing masks indoors, especially if they’re in crowded, poorly ventilated spaces. That’s what the [Centers for Disease Control and Prevention] recommends. And I think that’s a very important and effective way of reducing transmission, protecting yourself as well.

“You know, in terms of mandates, that’s something that we’ve always felt strongly should be done by local officials, mayors, governors, local health officials, and we’re seeing different officials take different tactics. And I think that’s actually appropriate given that we have a very diverse country with different transmission patterns and and willingness to kind of engage in-in wearing masks.”

Jha was also asked about monkeypox, which on Saturday the World Health Organization declared a “public health emergency of international concern”. Would the Biden administration declare a pandemic?

“Pandemics are declared by the World Health Organization,” Jha said, “and I actually applaud the World Health Organization for declaring that public health emergency of international concern. We are seeing outbreaks that are out of control in many, many parts of the world. It’s very important that we get our arms around this thing.

“In the US right now, we’re looking at public health emergency as something that [the health department] might … invoke but it really depends on what does that allow us to do. Right now we have over 2,000 cases, but we have ramped up vaccinations, ramped up treatments, ramped up testing, and we’re going to continue to look at all sort of policy options. Right now, we think we can get our arms around this thing but obviously if we need further tools we will invoke them as we need them.”

Jha said he thought monkeypox could be contained.

“The way we contain monkeypox is we have a very simple, straightforward strategy on this, which is: make testing widely available. We have done that. And now testing is far more frequent and common.

Answering the charge that the US was caught flat-footed by monkeypox, Jha said: “What I would acknowledge is that when we started two months ago, we had a limited supply of vaccines. We have obtained more than any other country, probably more than every other country combined. We have acted swiftly.”

Asked if people should be concerned about another infectious disease, polio, which has been detected in New York, Jha said: “There is a lot of surveillance that we do for polio, there’s wastewater surveillance that goes on, we are not seeing outbreaks of polio elsewhere.

“This one case has heightened everybody’s surveillance. But … CDC and the Department of Health of New York are doing an investigation to try to understand more, but I do not expect polio to become more widespread in the country, again, because so many Americans are vaccinated against this.”