RESUMO
Sixty-eight Saudi children, 17 to 19 months of age, were enrolled in a study to evaluate the safety and immunogenicity of Hemophilus influenzae type B capsular polysaccharide diphtheria toxoid (PRP-D) conjugate vaccine. Adverse reactions to the vaccine were determined through a questionnaire administered to the parents. Local and systemic reactions to the vaccine were mild and resolved within 24 to 48 hours. PRP antibody levels were measured prior to and one to two months following immunization. PRP antibody levels in the pre-immunization sera of 77% of subjects were below the level associated with immediate protection (>/=0.15 microg/ml), and 88% were below the level associated with long-term protection (>/=1 microg/ml) from Hemophilus influenzae type B (HIB) disease. After one dose of PRP-D vaccine, 100% of recipients achieved antibody levels of >/=0.15 microg/ml, and 85% achieved levels of >/=1 microg/ml. The geometric mean level of antibody after immunization (5.66 microg/ml) was significantly higher than that before immunization (0.098 microg/ml). All subjects had a twofold or greater increase in antibody level in response to the vaccine. We conclude that PRP-D is a safe and highly immunogenic vaccine in this age group of Saudi children.
