SAFETY AND IMMUNOGENICITY OF 3 DOSES OF A 5-VALENT PNEUMOCOCCAL CONJUGATE VACCINE IN CHILDREN YOUNGER THAN 2 YEARS WITH AND WITHOUT HUMAN-IMMUNODEFICIENCY-VIRUS INFECTION

Objective. To assess the safety and immunogenicity of three doses of a five-valent (types 6B, 23F, 14, 18C, and 19F) pneumococcal conjugate vaccine (PCV) among children younger than 2 years who are and are not infected with human immunodeficiency virus (HIV). Methods. A convenien ce sample of 18 HIV-infected children 2 years and younger (mean, 12.9 months) received three doses (each separated by 2 months) of PCV. An a dditional convenience sample of 33 non-HIV-infected children of virtua lly identical age, race, and sex as the HIV-infected group were random ized in a double-blind fashion to receive three doses of PCV or saline placebo. Safety data were collected for 72 hours after each vaccinati on. Sera were obtained before each and 1 month after the third vaccina tion to determine vaccine type-specific immunoglobulin G pneumococcal antibody titers by an enzyme-linked immunosorbent assay. Results. Seve nteen HIV- and 30 non-HIV-infected children completed the study. The P CV was well tolerated by both HIV- and non-HIV-infected children. No s ignificant differences in local or systemic reactions were noted betwe en HIV- and non-HIV-infected PCV or placebo recipients. Three doses of PCV were immunogenic, as evidenced by 16- to 659-fold increases in ty pe-specific geometric mean antibody titers over prevaccination levels in HIV- and non-HIV-infected children. With respect to an arbitrary pr otective level, 78% of the antibody titers from HIV-infected children and 88% of the titers from non-HIV-infected children were 1.0 mu g/mL or greater 1 month after the third PCV dose. HIV-infected children wit h milder disease (Centers for Disease Control and Prevention classes N 1-2, A1-2, and B1) were more likely to have protective antibody titers after the first and second PCV doses than HIV-infected children with more advanced disease (Centers for Disease Control and Prevention clas ses N3, A3, B2-3, and C1-3). However, after the third PCV dose, these differences disappeared. Conclusion. Three doses of PCV seem safe and immunogenic in both HIV- and non-HIV-infected children younger than 2 years. This type of vaccine should result in a marked reduction in sys temic pneumococcal disease in both HIV- and non-HIV-infected children. Given the high incidence of invasive pneumococcal disease in HIV-infe cted children, this vaccine may markedly improve the quality of life f or this unfortunate group of children.