This vaccine is also recommended for Adults with anatomic or functional asplenia and those scheduled for elective splenectomy if they are unimmunized (ie, if they have not previously received a primary series plus booster dose or ≥ 1 dose of Hib vaccine after age 14 months), although some experts suggest giving a dose before elective splenectomy regardless of vaccination history Immunocompromised adults (eg, because of cancer chemotherapy or HIV infection) if they are unimmunized People who have had a hematopoietic stem cell transplantation regardless of their vaccination history Contraindications and Precautions of Hib Vaccine The main contraindication for Hib vaccines is A severe allergic reaction (eg, anaphylaxis) after previous dose or to a vaccine component The main precaution with Hib vaccines is Moderate or severe illness with or without a fever (vaccination is postponed until the illness resolves) Dose and Administration of Hib Vaccine The Hib vaccine dose is 0.5 mL IM.