Response of human immunodeficiency virus-exposed and -infected infants to Haemophilus influenzae type b conjugate vaccine
R. M. Rutstein, B. J. Rudy and A. Cnaan
Division of General Pediatrics, Children's Hospital of Philadelphia (Pa), USA.
OBJECTIVE: To evaluate the response of human immunodeficiency virus
(HIV)-infected and -exposed infants to the primary series and booster dose
of Haemophilus influenzae type b (Hib) conjugate vaccine. DESIGN:
Retrospective study. PATIENTS AND SETTING: The HIV-exposed and -infected
infants who were attending the Special Immunology Family Clinic at The
Children's Hospital of Philadelphia (Pa). MAIN OUTCOME MEASURES: Geometric
mean antibody titers (GMTs) to Hib polyribosyl ribitol phosphate capsular
antigen were assessed after the primary series and again after the 15-month
booster doses. In addition, the percentages of patients who responded with
polyribosyl ribitol phosphate antibody levels greater than both 0.15 and
1.0 mg/L were compared between groups. RESULTS: After the 3-dose primary
series, the GMTs were lower in the HIV-infected infants compared with those
in the HIV-exposed, uninfected infants (0.86 vs 2.30, P = .02). Forty-six
percent of the HIV-infected infants mounted a response ( > 1.0 mg/L)
compared with that in 79% of the HIV-exposed infants (P = .05). Among the
HIV-infected infants, there was no difference in the GMTs based on CD4+
cell counts or HIV-related symptoms. After the 15-month booster dose, the
GMTs were not significantly different in the HIV-infected and -exposed
infants. As a group, the HIV-infected infants responded to the booster dose
with a 2-fold increase in the GMTs, and significantly more of these infants
had antibody concentrations above 1.0 mg/L compared with their response to
the primary series (62% vs 38%, P = .02). CONCLUSIONS: Most of the
HIV-infected infants responded to the primary series of Hib conjugate
vaccine with antibody concentrations greater than 0.15 mg/L, but the GMTs
were significantly lower than those in the uninfected infants. The primary
series of Hib conjugate vaccine appeared to be capable of inducing specific
immunologic memory in the HIV-infected infants. The HIV-infected infants
had a significant response to a booster dose of Hib conjugate vaccine, as
measured by using the GMTs and the percentage of infants with antibody
concentrations greater than 1.0 mg/L. The duration of protective titers
will need to be followed in this population of patients who are at a high
risk for serious bacterial disease.
