Act-HIB Dosing for Adults
For most healthy adults, Act-HIB (Haemophilus influenzae type b vaccine) is not routinely recommended and therefore has no standard dosing schedule. 1
When Act-HIB IS Indicated in Adults
Act-HIB should be administered as a single 0.5 mL intramuscular dose in the following high-risk adult populations 1:
Anatomic or Functional Asplenia
- One dose of any licensed Hib conjugate vaccine (including Act-HIB) for unimmunized adults with asplenia 1
- If elective splenectomy is planned, administer at least 14 days before the procedure 1
- Some experts recommend giving a dose prior to elective splenectomy regardless of prior vaccination history 1
Hematopoietic Stem Cell Transplant Recipients
- Three-dose series administered 4 weeks apart, starting 6-12 months after successful transplant 1
- This applies regardless of previous Hib vaccination history 1
- Each dose is 0.5 mL intramuscularly 1
HIV-Infected Adults
- Hib vaccine is NOT recommended for HIV-infected adults, as the incidence of Hib infections in this population is low 1
- This contrasts with HIV-infected children, who should receive one dose if unimmunized 1
Important Clinical Caveats
Do not administer Hib vaccine to adults with other immunocompromising conditions (such as immunoglobulin deficiency or complement deficiency) unless they also have asplenia or are HSCT recipients, as these are the only validated adult indications 1.
Timing considerations for immunosuppressed patients:
- Avoid vaccination within 14 days of starting chemotherapy or radiation therapy 1
- Patients vaccinated during immunosuppressive therapy should be considered unimmunized 1
- Revaccinate at least 3 months after completing chemotherapy (except HSCT recipients who follow the special 3-dose protocol) 1