Hib vaccine is not routinely recommended for healthy adults 19 years and older, even if the person did not receive Hib vaccine as a child. However, ACIP recommends that one dose of Hib vaccine should be administered to persons who have anatomical or functional asplenia or sickle cell disease or are undergoing elective splenectomy if they have not previously received Hib vaccine. Hib vaccine should be administered 14 or more days before splenectomy if possible. Recipients of a hematopoietic stem cell transplant should be vaccinated with a 3-dose series of Hib vaccine 6 to 12 months after a successful transplant, regardless of vaccination history; at least 4 weeks should separate doses. Hib vaccine is not recommended for adults with HIV infection since their risk for Hib disease is low.