The campaign has consulted physicians and health experts about safeguarding Mr. Biden, who at 77 falls squarely into a high-risk group for the coronavirus. Irwin Redlener, a clinical professor at Columbia University’s Mailman School of Public Health, said he had spoken with the campaign about health precautions, including how to handle the possibility that members of Mr. Biden’s traveling staff had been exposed.
“In terms of the safety of the staff, the candidate, what did they need to know?” said Dr. Redlener, who previously served on Mr. Biden’s public health advisory committee.