Recommendations of the Immunization Practices
Advisory Committee
Supplementary Statement: Change in Administration Schedule for
Haemophilus b Conjugate Vaccines
In December 1989, the Food and Drug Administration licensed a
new vaccine--Haemophilus b Conjugate Vaccine (Meningococcal
Protein Conjugate) (PRP-OMP)--for routine use in children greater
than or equal to 18 months of age. The license contains the
statement that PRP-OMP can be given to children as young as 15
months of age when "it is expected that the child will not return
at 18 months of age for Haemophilus b immunization." Since
December 1989, two vaccines previously licensed for use in
children at 18 months of age--Haemophilus b Conjugate Vaccine
(Diphtheria Toxoid Conjugate) (PRP-D) and Haemophilus b Conjugate
Vaccine (Diphtheria CRM
197 Protein Conjugate) (PRP-HbOC)--also have been approved for
use in children as young as 15 months of age.
Some differences in immunogenicity may exist among different
Haemophilus b conjugate vaccines (1). However, further studies
are needed to confirm any differences and evaluate their clinical
relevance. In addition, immunogenicity is age-dependent, with
immune response improving with increasing age (Table 1).
Approximately 7% of all Haemophilus influenzae type b disease
in children less than 5 years of age occurs in children 15-17
months of age. Because of the substantial immunogenicity of the
Haemophilus b conjugate vaccines when given to children in this
age group, the Immunization Practices Advisory Committee (ACIP)
now recommends routine vaccination of children at 15 months
instead of at 18 months of age using any of the Haemophilus b
conjugate vaccines licensed for use. Prior ACIP recommendations
for the use of PRP-D are applicable to the newer conjugate
vaccines (2).
References
Wenger JD, Ward JI, Broome CV. Prevention of Haemophilus
influenzae type b disease: vaccines and passive prophylaxis. In:
Remington JS, Swartz MN, eds. Current clinical topics in
infectious diseases. Vol 10. Boston: Blackwell Scientific
Publications, 1989:306-39.
ACIP. Update: prevention of Haemophilus influenzae type b
disease. MMWR 1988;37:13-6.
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