On Dec 22, 1987, the first conjugate vaccine was licensed by the FDA for the prevention of infections due to Haemophilus influenzae type b. This vaccine is a conjugate of H influenzae type b capsular polysaccharide and diphtheria toxoid and is officially designated as Haemophilus b conjugate vaccine (diphtheria toxoid-conjugate). The purpose of this statement is to provide background information, perspective, and recommendations for the use of this product.
H influenzae type b is a major cause of serious infections in infants and children, about 30% of which occur in children 18 months of age and older.1,2 American licensure of the "first-generation" vaccines, the Haemophilus b polysaccharide vaccines or "plain" capsular polysaccharide vaccines (often referred to as PRP), was based on a field trial conducted in Finland.3 In this study which started in 1975, 48,977 children 3 to 71 months of age received a polysaccharide vaccine similar to those that were later licensed in the United States. Protection was correlated with the production of an anticapsular antibody concentration that exceeded 1.0 µg/mL in serum obtained 3 weeks after immunization. In children immunized at 18 to 71 months of age, the efficacy was 90% (95% confidence interval, 55% to 98%).2,3 Among those immunized at 18 to 23 months of age, the small number of cases in the vaccinees and the control group precluded a definitive conclusion about vaccine efficacy. In 8,453 children immunized at 2 years of age (24 to 35 months), the efficacy was 80% (95% confidence interval, 7% to 94%).4
- Copyright © 1988 by the American Academy of Pediatrics