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Questions and Answers
NIP Answers Your Questions
Haemophilus influenzae type b
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General Questions

  • When children less than 24 months of age are infected with Hib, why does the infection not confer immunity but the vaccine does?

    When a young child is infected with Hib disease, the child is exposed to the polysaccharide molecules and a young child’s immune system is not mature enough to respond. A child who is vaccinated is exposed to polysaccharide molecules that have been conjugated to a protein. Their immune system responds much better to a conjugated polysaccharide than to a polysaccharide alone. This is a case where the immune response to the vaccine is better than the immune response to the “natural infection.” Pink Book Chapter: Hib. (2/20/03)

  • If a child over 2 years of age and has had Hib disease, should they be vaccinated?

    We hope this will not happen since Hib disease has become rare in the U.S. Most cases are occurring in younger children who have not been vaccinated.

    Children younger than 2 years of age who develop Hib infection do not respond well to polysaccharide stimulation that occurs during infection and do not develop immunity as a result of infection. Therefore, we recommend that these children should complete the Hib series after recovery from the infection.

    Using the same rationale, children 2 years of age or older who develop Hib infection should be capable of developing antibody to the bacteria. So presumably the child would not need further vaccine. On the other hand, the vaccine would not hurt the child. If there is any doubt about the strain of Haemophilus influenzae and whether the infection was truly caused by type b, then you should take the conservative approach and vaccinate the child. (02/26/04)

  • Does Hib vaccine provide life-long immunity?

    Hib conjugate vaccine has been used for more than ten years now. Breakthrough Hib disease has not been reported in older children. Therefore, immunity persists for more than ten years. We will continue to monitor for breakthrough disease in older people. (2/20/03)

  • Should an adult who has had a stem cell transplant receive Hib vaccine even though the vaccine is licensed for children under 72 months of age?

    Yes. The Hematopoietic Stem Cell Transplant recommendations that came out a few years ago specifically recommended that Hib should be given to these adults (Vaccination of Hematopoietic Stem Cell Transplant Recipients – see pages 5-6). A single dose of Hib vaccine is also recommended for adults who have a non-functioning spleen or no spleen (ACIP recommendations for immunodeficient persons – see page 8 and Table 2). We don’t recommend the vaccine for very many adults, but for people without spleens and those who have had a stem cell transplant, a single pediatric dose of Hib should be administered. (2/20/03)

  • Should we give Hib vaccine to persons with a cochlear implant if they are 5 years of age or older?

    Available information does not suggest children or adults aged 5 years or older with cochlear implants need Hib vaccination. There is no specific contraindication to using Hib vaccine in unvaccinated older children and adults, and health care providers may consider its use in cochlear implant recipients. However, there also are no data demonstrating clinical benefit of Hib vaccination for persons with cochlear implants outside the recommended age range. If Hib vaccine is used in persons aged 5 years of older, a single intramuscular injection is all that is needed. For more information about use of Hib vaccine visit this Jan. 11, 1991 [40(RR01);1-7] MMWR article located at (8/21/03)



Comvax Trihibit    

  • If a 7 month old child received two doses of ActHIB and then received a dose of TriHIBit at 6 months of age. Does the Hib dose given as TriHIBit need to be repeated, and if so, when?

    Repeat the dose. Any dose of Hib given as TriHIBit under 12 months of age is not valid. A valid 3rd dose of single-antigen Hib can be given 4 weeks after the invalid dose. Pink Book Chapter: Hib and ACIP General Recommendations. (2/20/03)

  • If a child received a primary series with TriHIBit and another dose of TriHIBit at 18 months of age, does the child need another dose of Hib?

    This is difficult to answer because there are really no data. The Hib doses given for the primary series are invalid since TriHIBit was used. TriHIBit should not be used for the booster dose unless the child has received at least one prior dose of Hib. Since the prior doses were invalid, the booster dose is technically invalid. Therefore, a valid booster dose of single antigen Hib should be given. Pink Book Chapter: Hib. (2/20/03)

  • If PedvaxHIB is given for the 1st and 2nd doses, can the series be completed by adding one dose of another brand of Hib after 12 months of age?

    The primary series for PedvaxHib (PRP-OMP) is 2 doses. Any licensed conjugate vaccine may be used for the booster dose regardless of what was received in the primary series. Pink Book Chapter: Hib. (2/20/03)

  • If a child received two doses of Hib vaccine and the second dose was given at 13 months of age, does the child need a third dose?

    It depends on when the first dose was administered. If both doses were administered at one year of age or after, then 2 doses are all the child needs. If the first dose was administered before one year of age and the second dose at 13 months of age, then the child needs one more dose based on the Hib schedule in the Pink Book. Pink Book Chapter: Hib. (2/20/03)

  • Is this a valid schedule: Hepatitis B at birth; Comvax at 2 months; Hib at 4 months; Comvax at 6 months; and Hib at 12-15 months?

    Yes. This allows for completion of the Hepatitis B and Hib series without violating minimum ages and intervals. (2/20/03)

  • Does a child need a 4th Hib if he received 3 Comvax. Why or why not?

    No. A 3-dose Comvax series is a complete Hepatitis B series AND a Hib series, as long as the minimum ages and minimum intervals for the individual antigens are observed. Comvax contains PedvaxHIB, which is a 2-dose primary series followed by a booster dose after 12 months of age. If any other brand of Hib is used for the primary series (either of the first two doses), then the child will need a total of 4 Hib doses. (03/04/04)

  • If Comvax is given at 2 and 4 months and the patient isn’t available at 12-15 months, what should we do when they return to the clinic later?

    You can administer any brands of single-antigen Hepatitis B and Hib vaccines or you can use Comvax, as long as the child is not over 59 months of age. If the child is older than 5 years of age, Hib vaccine is not indicated and single-antigen Hepatitis B vaccine should be used for the 3rd dose. (2/20/03)

  • In the discussion of Comvax it was stated that you can "use when either antigen is indicated." Shouldn’t Comvax be used when both Hepatitis B and Hib are needed and single antigen Hepatitis B or Hib used if only one component is due?

    You can use single antigen vaccine when only one of the vaccines is indicated or you can use a combination vaccine. ACIP states that licensed combination vaccines may used whenever any component of the combination is indicated and the vaccine’s other components are not contraindicated. Childhood Immunization Schedule (see Main footnote) (2/20/03)

  • If a child received Hepatitis B vaccine at birth and Hib vaccine at 2 and 4 months of age, can you give Comvax at 6 months without having to give another Comvax again?

    Yes, but the child will still need another dose of Hepatitis B vaccine no sooner than 8 weeks after the 6-month dose of Comvax, and a booster dose of Hib at 12-15 months of age. (2/20/03)

  • Does a child need a 4th dose of Hib if Comvax is used?

    Comvax contains PedvaxHIB. The primary series of PedvaxHIB consist of two primary doses at 2 and 4 months followed by a booster dose at 12-15 months, which is the recommended schedule for Comvax. If any Hib vaccine other than Comvax or PedvaxHIB is used for the first or second dose of Hib at 2 or 4 months of age, then a third dose of any licensed Hib is recommended at 6 months of age to complete the primary series. The child will then need a booster dose of Hib at 12-15 months of age, which can be Comvax or any licensed Hib vaccine, (8/21/03)

  • Is it appropriate to administer Hib-Hep B (Comvax) at 2 and 6 months to an infant who had hepatitis B vaccine at birth?

    No, you are depriving the child of the dose of Hib at 4 months of age. It is important to give the Hib at 4 months of age because one dose at 2 months does not offer adequate protection and very young children are the ones at greatest risk for Hib disease. If the child received a birth dose of hepatitis B vaccine and you are using Comvax, then give Comvax at 2 and 4 months of age with a final dose at 12-15 months of age. Don’t delay the schedule and deny the child the complete benefit of the Hib component. (02/26/04)

  • If an 18-month-old received a primary series with TriHIBit, should the child receive one more dose of Hib?

    Yes, this child does not have any valid doses of Hib at this time because TriHIBit was used. You can count DTaP doses given as TriHIBit before 12 months of age, but not the Hib doses. Hib vaccine is recommended through 59 months of age and the lapsed Hib schedule states that any child 15 to 59 months of age with an incomplete schedule should receive one dose of Hib. This child should be given this protection. Pink Book Chapter: Hib. (2/20/03)

  • What should we say to private providers who don’t give the last dose of Hib vaccine until the 18-month check-up?

    The ACIP and the American Academies of Pediatrics and Family Physicians recommend that the last dose of Hib vaccine should be administered between 12-15 months of age. Children under 2 years of age are at greatest risk for Hib disease. The earlier they are completely vaccinated, the better they are protected. (2/20/03)

  • If a child has completed a primary series of Hib vaccinations (2-3 doses) before 1 year of age, but has not received the booster dose between 12-15 months, at what age does the child no longer need to receive the booster dose?

    Hib vaccine is no longer routinely recommended once a child reaches 5 years of age.Pink Book Chapter: Hib. (2/20/03)

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This page last modified on April 22, 2004


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