Volunteers answer staffing shortage for vaccination clinics, expose growing need Maine hospitals have called in volunteers to help vaccinate thousands of front-line health care workers, indicating a potential shortage of trained vaccinators and others to carry out a mass inoculation. Share Dr. Peggy Pennoyer and her husband, Dr. Don Endrizzi, both recently retired physicians, have returned to Maine Medical Center in Portland as volunteers to help administer COVID-19 vaccines. Derek Davis/Staff Photographer Drs. Peggy Pennoyer and Don Endrizzi came out of retirement this month to help Maine Medical Center launch an effort to vaccinate thousands of front-line health care workers against COVID-19.