Vaccine clinics in Prince William canceled, appointments to be rescheduled Monday, February 1, PWHD Vaccinations Scheduled Appointments: Clinics at Beacon Hall on the Science and Technology Campus of George Mason University in Manassas, and Potomac Middle School in Woodbridge have been canceled due to ongoing inclement weather. If you are scheduled to receive your COVID-19 vaccine at GMU Beacon Hall, or Potomac Middle School, on Monday, February 1st, your appointment has been canceled due to potentially hazardous weather conditions. Please check your email for rescheduling instructions or call the PWHD Call Center after 9:00 AM Monday for assistance. PWHD Call Center: (703) 872-7759