; (6) modernizing infrastructure or curriculum at an existing allopathic or osteopathic school of medicine or branch campus thereof; (7) expanding infrastructure or curriculum at existing an allopathic or osteopathic school of medicine or branch campus; and (8) other activities that the Secretary determines further the development, improvement, and expansion of an allopathic or osteopathic school of medicine or branch campus thereof. (d) Definitions In this section: (1) The term branch campus means a geographically separate site at least 100 miles from the main campus of a school of medicine where at least one student completes at least 60 percent of the student’s training leading to a degree of doctor of medicine. (2) The term institution of higher education has the meaning given to such term in section 101(a) of the Higher Education Act of 1965. (e) Authorization of appropriations To carry out this section, there is authorized to be appropriated $1,000,000,000, to remain available until expended. . 616. GAO study on public health workforce (a) In general The Comptroller General of the United States shall conduct a study on the public health workforce in the United States during the COVID–19 pandemic. (b) Topics The study under subsection (a) shall address— (1) existing gaps in the Federal, State, local, Tribal, and territorial public health workforce, including— (A) epidemiological and disease intervention specialists needed during the pandemic for contact tracing, laboratory technicians necessary for testing, community health workers for community supports and services, and other staff necessary for contact tracing, testing, or surveillance activities; and (B) other personnel needed during the COVID–19 pandemic; (2) challenges associated with the hiring, recruitment, and retention of the Federal, State, local, Tribal, and territorial public health workforce