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Article
February 27, 1991

Protective Efficacy of Haemophilus influenzae Type b Polysaccharide and Conjugate Vaccines in Children 18 Months of Age and Older

Author Affiliations

From the UCLA Center for Vaccine Research, Harbor-UCLA Medical Center, UCLA School of Medicine (Drs Greenberg, Vadheim, Christenson, and Ward and Mss Bordenave and Ziontz), and the Los Angeles (Calif) County Department of Health Services (Dr Waterman).

From the UCLA Center for Vaccine Research, Harbor-UCLA Medical Center, UCLA School of Medicine (Drs Greenberg, Vadheim, Christenson, and Ward and Mss Bordenave and Ziontz), and the Los Angeles (Calif) County Department of Health Services (Dr Waterman).

JAMA. 1991;265(8):987-992. doi:10.1001/jama.1991.03460080057032
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)

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