Immunogenicity of a Booster Dose of Quadrivalent Meningococcal Conjugate Vaccine in Previously Immunized HIV-Infected Children and Youth

Background. The US Advisory Committee on Immunization Practices recommends a booster dose of quadrivalent meningococcal conjugate vaccine (MCV4) after initial immunization for patients at high risk for meningococcal infection. Methods. The International Maternal Pediatric Adolescents AIDS Clinical Trials (IMPAACT) P1065 trial evaluated the use of MCV4 in human immunodeficiency virus (HIV)-infected children and youth. The final step of this trial was an open-label study of an MCV4 booster dose 3.5 years after primary MCV4 immunization. Antibody titers were evaluated at the time of the booster vaccine and 1, 4, and 24 weeks after the booster. Immunogenicity was measured by rabbit serum bactericidal antibody (rSBA) against each meningococcal serogroup. Immunologic memory was defined as either seroprotection (rSBA titer >= 1:128) or a >= 4-fold increase 1 week after the booster dose. Primary response was defined as either a >= 4-fold response or seropositivity 4 weeks after the booster in the absence of immunologic memory. Adverse events were assessed for 4 weeks after the booster dose. Results. Of 174 participants with serology results at entry and 1 and 4 weeks later, the percentage with protective antibody levels at entry varied according to serogroup, ranging from a low of 26% for serogroup C to a high of 68% for serogroup A. A memory response to at least 1 serogroup occurred in 98% of the participants: 93% each for serogroups A and Y, 88% for serogroup C, and 94% for serogroup W-135; 83% had a memory response to all 4 serogroups. Overall, rates of any memory or primary response were >= 90% for all serogroups. No serious adverse events were encountered. Conclusions. A booster dose of MCV4 elicited a memory response in 88% to 94% of previously immunized HIV-infected participants depending on serogroup, including those who lacked a protective titer level for that serogroup before booster vaccination.