Sir.—The study in the July 1991 issue of AJDC on dose-related immunogenicity of one of the conjugate Haemophilus influenzae type b (Hib) vaccines could merit from a more detailed analysis of the data.1 The data presented in several aggregates could be divided into smaller groups for a better appreciation of the effectiveness of the vaccine. The age grouping of the children does not take into account an age-dependent response to conjugate vaccines reported for another vaccine given during the first year of life.2 Secondly, geometric mean titers do not give a sense of the protection afforded to the vaccinated population.
The pediatric section of the Marshfield (Wis) Clinic performed a similar dose-response study with the conjugate Hib vaccine oligosaccharide-CRM197 (HibTITER, Lederle-Praxis Biologicals, Pearl River, NY), in which a cohort of children was vaccinated, starting at age 2 months. Assays for anti—polyributylribitol phosphate (PRP) antibody concentrations were
SULLIVAN BJ. Immune Response to Hib Conjugate Vaccine. Am J Dis Child. 1992;146(2):145-146. doi:10.1001/archpedi.1992.02160140011005