US Vice President Mike Pence did not wear a face mask during a Tuesday visit to the Mayo Clinic, violating the prestigious medical center's policy despite his team being warned in advance.
Video showed Pence visiting staff and a patient in a crowded hospital room without wearing a mask.
The Minnesota-based center's policy states: "Part of our protocol for ensuring your safety is to require all patients, visitors and staff to wear a face covering or mask while at Mayo Clinic to guard against transmission of COVID-19."
The clinic said in a statement that it had "shared the masking policy with the VP's office."
The Centers for Disease Control and Prevention (CDC) recently updated its advice to recommend that people wear cloth face coverings in public settings where it is difficult to maintain adequate physical distance at all times, such as in grocery stores and pharmacies.
This is because a very high proportion of people infected with the coronavirus are believed to be asymptomatic and because recent research has shown that it may in certain circumstances be possible to infect others through normal speaking and breathing.