A: If you are moderately or severely immunocompromised, you can schedule a third dose through MyLVHN, the patient portal, by calling the COVID-19 Vaccine Hotline at 833-584-6283 (833-LVHN-CVD), or going to one of LVHN's COVID-19 Vaccine Clinics. The third shot should be at least 28 days after the second dose shot..