The immunogenicity of Haemophilus influenzae type b conjugate (HbOC) vaccine in human immunodeficiency virus-infected and uninfected infants.

Enzyme-linked immunosorbent assay polyribosyl ribitol phosphate (PRP) antibody responses to Haemophilus influenzae type b conjugate vaccine (HbOC) given at 2, 4 and 6 months of age were retrospectively compared in 23 human immunodeficiency virus (HIV) and 24 non-HIV-infected infants. HIV-infected infants were divided into those who were P1 (asymptomatic) or P2 (symptomatic) by 1 year of age. The P2 group was further divided into P2A (mildly symptomatic) and > P2A (rapidly symptomatic) by 1 year of age. The post-third HbOC dose geometric mean antibody titer to PRP was significantly lower in 12 P2 infants (0.43 microgram/ml) than either the 11 P1 infants (5.03 micrograms/ml, P < 0.05) or the 24 non-HIV infected infants (3.43 micrograms/ml, P < 0.05). Within the P2 group, the geometric mean antibody titer to PRP was significantly higher in 5 P2A infants (1.63 micrograms/ml) compared with 7 infants who were > P2A (0.17 microgram/ml, P < 0.05). After the third HbOC dose, PRP antibody titers were > or = 1.0 micrograms/ml for 4 of 12 P2 compared with 9 of 11 P1 infants (P < 0.05). Within the P2 group, PRP antibody titers were > 1.0 micrograms/ml for 4 of 5 P2A compared to 0 of 7 infants who were > P2A (P < 0.05). HIV-infected infants with PRP antibody titers > or = 1.0 micrograms/ml after the third HbOC dose had significantly higher mean CD4 counts (2842 cells/mm3) at the time of the third HbOC dose than those with lower PRP titers (1655 cells/mm3) (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)