Protective Efficacy of Haemophilus influenzae Type b Polysaccharide and Conjugate Vaccines in Children 18 Months of Age and Older
- David P. Greenberg, MD;
- Constance M. Vadheim, PhD;
- Nanette Bordenave, MPH;
- Leslie Ziontz, MPH;
- Peter Christenson, PhD;
- Stephen H. Waterman, MD;
- Joel I. Ward, MD
Abstract
To evaluate the protective efficacy of polyribosylribitol phosphate (PRP) and polyribosylribitol phosphate—diphtheria toxoid (PRP-D) vaccines in children 18 to 59 months of age, we conducted a case-control study in Los Angeles (Calif) County between July 1, 1988, and July 31, 1989. Seventy-nine children with invasive Haemophilus influenzae type b disease 18 to 59 months of age were identified, and 212 controls were selected by random-digit telephone dialing methods. Cases and controls were stratified by age and month of disease onset of the case. Seventeen PRP vaccine failures and two PRP-D vaccine failures occurred more than 2 weeks after vaccination. The PRP vaccine was shown not to be effective (point estimate - 47%; 95% confidence interval, - 307% to 47%), but the PRP-D vaccine was 88% protective (95% confidence interval, 42% to 97%). Adjustment of the efficacy estimates for potential confounding variables did not change the results significantly. The PRP-D vaccine provided significantly better protection than the PRP vaccine against invasive H influenzae type b disease in this population.
(JAMA. 1991;265:987-992)
Footnotes
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Reprint requests to UCLA Center for Vaccine Research, Harbor-UCLA Medical Center, 1124 W Carson St, Bldg E-6, Torrance, CA90502 (Dr Greenberg).
