Vice-President Mike Pence has appeared without wearing a face mask while visiting the Mayo Clinic in Minnesota despite the medical centre’s own rules that visitors wear personal protective equipment.
In a deleted tweet, the Mayo Clinic said Mike Pence had been notified in advance of its policy requiring masks.
The vice-president leads the White House coronavirus taskforce.
The government’s own coronavirus-prevention advice is that people should wear face coverings “in public settings where other social distancing measures are difficult to maintain”.
The Mayo Clinic itself requires all patients and visitors to its medical centers to wear a mask or face covering.
VP Pence’s visit came on the same day that the US coronavirus caseload topped one million and the number of deaths surpassed 57,000.
President Donald Trump has himself previously said he has no plans to wear a mask.
The vice-president defended his decision to flout hospitals rules as necessary in order to meet with staff and patients.
He said: “As vice-president of the United States, I’m tested for the coronavirus on a regular basis, and everyone who is around me is tested for the coronavirus.
“And when the CDC issued guidelines about wearing a mask, it was their recognition that people that may have the coronavirus could prevent the possibility of conveying the virus to someone else by wearing a mask.
“And since I don’t have the coronavirus, I thought it would be a good opportunity for me to be here, to be able to speak to these researchers, these incredible healthcare personnel, and look them in the eye and say thank you.”
According to news website Axios, Mike Pence has never once worn a mask while in public since the pandemic began while continuing to travel throughout the country.
A Mike Pence aide was the first White House member to test positive for the virus in late March.