THE IMMUNOGENICITY OF HAEMOPHILUS-INFLUENZAE TYPE-B CONJUGATE VACCINES IN CHILDREN BORN TO HUMAN IMMUNODEFICIENCY VIRUS-INFECTED WOMEN

Background. Immunocompromise caused by HIV-1 infection increases the i mportance of receipt of routine childhood vaccines to prevent infectio ns such as invasive Haemophilus influenzae type B (Hib) disease. The o bjectives of the study were to evaluate the immunogenicity of Hib conj ugate vaccines among HIV-infected children according to clinical and i mmunologic disease progression as well as viral load. Methods. The con centration of antibody to polyribosylribitol phosphate (PRP) was measu red at similar to 9 and 24 months of age in plasma specimens from chil dren of HIV-infected women enrolled in the Women and Infants Transmiss ion Study. Results. Among 227 children (35 HIV-infected, 192 uninfecte d) at the 9-month study visit who were known to have received age-appr opriate immunization with CRM197 mutant Corynebacterium diphtheriae pr otein-conjugated Hib vaccine, geometric mean antibody concentrations w ere lower among HIV-infected children (1.64 mu g/ml) than among uninfe cted children (2.70 mu g/ml), although the difference was not statisti cally significant. Anti-PRP antibody concentrations did not vary signi ficantly among these HIV-infected children with predominantly mild-mod erate disease progression according to clinical category, immunologic stage or viral load (P greater than or equal to 0.48). The proportion of children with antibody concentrations greater than or equal to 1.0 mu g/ml did not vary significantly according to HIV infection status ( 73% uninfected, 74% infected) or, if infected, clinical or immunologic disease progression or viral load. Similar results were obtained amon g 127 children (17 HIV-infected, 110 uninfected) eligible for analysis at the 24-month study visit. Changes in antibody concentrations over time (between 9 and 24 months of age) did not differ significantly amo ng 10 HIV-infected as compared with 72 uninfected children (P = 0.81). Conclusions. These results suggest that HIV-infected children with pr edominantly mild-moderate disease progression respond reasonably well in terms of a quantitative antibody response to Hib conjugate vaccines during the first 2 years of life. Research to further characterize th e immune response to Hib conjugate vaccines and to further delineate t he ''durability'' of anti-PRP antibody concentrations beyond 2 years o f life should be pursued.