We studied the effect of maternal HIV-exposure and timing of antiretroviral treatment (ART) in HIV-infected infants on antibody responses to combined diphtheria-toxoid–tetanus-toxoid–whole cell pertussis and Haemophilus influenzae type b conjugate vaccine (HibCV) and monovalent hepatitis B vaccine (HBV).
HIV-uninfected infants born to HIV-infected (HEU) or HIV-uninfected (HUU) mothers were enrolled in parallel with HIV-infected children with CD4+ ≥25%, who were randomized to initiate ART immediately upon confirmation of HIV-infection (ART-Immed) or when clinically and/or immunologically indicated (ART-Def). Infants received three doses of diphtheria-toxoid–tetanus-toxoid -wP-HibC/HBV at 7.3, 11.4 and 15.4 weeks of age. Antibody to diphtheria-toxoid, tetanus-toxoid, pertussis toxin, filamentous hemagglutinin (FHA) and hepatitis B surface antigen (HBsAg) were measured by Luminex multiplex-immunoassay and polyribosyl-ribitol phosphate (PRP) antibodies by standard ELISA and bactericidal assay.
Prevaccination antibody geometric mean concentrations (GMCs) were higher in HUU than HEU infants for tetanus-toxoid, but lower for HBsAg, diphtheria-toxoid and FHA. Postvaccination GMCs and proportion with seroprotective antibody levels or sero-conversion rates were similar between HUU and HEU infants for all vaccines. Postvaccination GMCs were higher in HUU for tetanus-toxoid, diphtheria-toxoid, HBsAg and FHA than ART-Immed infants; and for tetanus-toxoid, HBsAg and pertussis-toxoid than ART-Def infants. Nevertheless, there was no difference in proportion of HUU and HIV-infected infants who developed sero-protective vaccine-specific antibody levels postvaccination. The timing of ART initiation generally did not affect immune responses to vaccines between HIV-infected groups.
Vaccination with DTwP-HibCV/HBV of HEU and HIV-infected infants initiated on early-ART confers similar immunity compared with HUU children.