For ages 5 and above the Pfizer vaccine is given as a 2-dose series 3-8 weeks apart with a booster dose given 5 months later. In patients 6months-4 years old, the Pfizer vaccine is given as a 3-dose series with NO booster. For people over age 50 or with immunocompromising conditions, a second booster dose is given 4 months after the first booster. Patients over 4 with an immunocompromising condition should receive a third additional dose in their primary vaccine series plus 2 booster doses.