Does 'related functions' in 42 U.S.C. § 233(a) immunize only medical care provision or broader health care-related activities?

QUESTION PRESENTED 42 U.S.C. § 233(a) provides Public Health Service officers and employees—and those deemed equivalent via § immunity from suit by making the Federal Tort Claims Act a plaintiff's exclusive remedy in “any . . . civil action or proceeding . . . resulting from the performance of medical, surgical, dental, or related functions” undertaken within their scope of employment. The question presented is: Does “related functions” in 42 U.S.C. § 233(a)’s recitation of immunized conduct mean functions related to medical, surgical, or dental functions—as the Ninth Circuit concluded in Friedenberg v. Lane County, 68 F.4th 1113 (9th Cir. 2023)—or, as the Fourth Circuit concluded, mean activity in “a field of health care outside of medicine, surgery, or dentistry,” App. 18a, such that § 233(a) immunizes only the “performance of the provision of health care.” App. 20a. i