And McCarthy said he has no doubt that Brigham and Women's fully weighed the risks and benefits of the surgery and lifelong immunosuppression before going forward.
"You're at a first-rate institution," he said. "These decisions are not going to be made casually."
McCarthy added that Frenchwoman Isabelle Dinoire, the world's first patient to have a face transplant, only went on immunosuppressants after her operation in her home country in 2005, and she appears to be doing well today.
After Dinoire became the first recipient of a partial face transplant in November 2005, similar surgeries in various countries have followed.
The first such surgery in the U.S., took place in December and repaired the face of a female patient using facial tissue from a dead female donor.
Most recently, on the weekend of April 4, a team of doctors at Henri Mondor hospital in Paris performed the world's first simultaneous partial-face and double-hand transplant on a 30-year-old burn victim.
Roger Sergel and Michelle Schlief contributed to this report.