After that, Dr. Carson said in the recent interview, “the Draft Ben movement started, and pretty soon I was getting thousands of petitions every week from around the country.”

Friends and colleagues have watched intently, generally feeling protective of him and explaining some startling statements as the words of a novice candidate caught in unforgiving media headlights.

One instance, however, has troubled his medical friends. In one Republican debate, Dr. Carson responded to a question about vaccines by noting that there was “no autism associated with vaccination,” but adding, “However, it is true that we are probably giving way too many in far too short a time.”

He also said that while vaccines that “prevent death or crippling” are important, “there are a multitude of vaccines which probably don’t fit in that category, and there should be some discretion in those cases.”

Vaccines prevent potentially lethal disease, and medical consensus strongly supports current vaccine timing and dosage. Ms. James said that when she heard Dr. Carson’s comments, “I was ranting and raving.” She said she later decided it might reflect another quality: “how he is open to compromise.”

Ms. James was personally affected by fallout from Dr. Carson’s public comments in 2013. Besides withdrawing as commencement speaker, he and Ms. James were asked to withdraw from accepting an award together from the American Academy of Physician Assistants. Reluctantly, they obliged.

“It certainly wasn’t the way that we wanted to end a very long career at Hopkins,” she said.

Months after Dr. Carson retired, a Hopkins party was held, kept off limits to the media. “We didn’t want this to be turned into a political thing,” Dr. Brem said. “We wanted this to be about Ben Carson — our Ben Carson.”