The efficacy in Navajo infants of a conjugate vaccine consisting of Haemophilus influenzae type b polysaccharide and Neisseria meningitidis outer-membrane protein complex.
METHODS
Several conjugate vaccines against Haemophilus influenzae type b have been developed in the search for one that induces protection even in young infants. We evaluated the safety and efficacy of a conjugate vaccine that links the H. influenzae type b capsular polysaccharide to the outer-membrane protein complex (OMPC) of Neisseria meningitidis serogroup B. We conducted a double-blind, placebo, controlled trial in Navajo infants, who are at high risk for systemic infections caused by H. influenzae type b. The infants were randomly assigned to receive the first dose of vaccine or placebo at 42 to 90 days of age and the second at 70 to 146 days of age.


RESULTS
Of the infants in the trial, 2588 were assigned to receive the vaccine and 2602 to receive placebo. The mean follow-up was 269 days in the vaccine group and 267 days in the placebo group. Before the age of 18 months, there was 1 systemic H. influenzae type b infection in the vaccine group, as compared with 22 in the placebo group (P less than 0.001; point estimate of efficacy, 95 percent; 95 percent confidence interval, 72 to 99 percent). Of the 22 H. influenzae type b infections in the placebo group, 13 were meningitis. Among the children who received both doses, there was 1 H. influenzae type b infection in the vaccine group (n = 2056) and 14 in the placebo group (n = 2105) (P less than 0.001; point estimate of efficacy, 93 percent; 95 percent confidence interval, 53 to 98 percent). The single infection in the vaccine group occurred at 15 1/2 months of age in an infant with osteomyelitis. Between the first and second doses there were no H. influenzae type b infections in the vaccine group and eight in the placebo group (P less than 0.005; point estimate of efficacy, 100 percent; 95 percent confidence interval, 41 to 100 percent).


CONCLUSIONS
The H. influenzae type b OMPC vaccine, administered at 2 and 4 months of age, is safe and induces a high rate of protection against invasive disease caused by H. influenzae type b in infants under the age of 18 months. Protection begins after the first dose.
Santosham
M
M
Center for American Indian and Alaskan Native Health, Department of International Health, Johns Hopkins University School of Hygiene and Public Health, Baltimore, MD 21205.
Wolff
M
M
Reid
R
R
Hohenboken
M
M
Bateman
M
M
Goepp
J
J
Cortese
M
M
Sack
D
D
Hill
J
J
Newcomer
W
W
D000917:Antibody Formation; D001425:Bacterial Outer Membrane Proteins / Q000009:adverse effects / Q000276:immunology; D001428:Bacterial Vaccines / Q000009:adverse effects / Q000276:immunology; D004311:Double-Blind Method; D005500:Follow-Up Studies; D006192:Haemophilus Infections / Q000517:prevention & control*; D018073:Haemophilus Vaccines; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007115:Immunization Schedule; D007198:Indians, North American; D007223:Infant; D009345:Neisseria meningitidis / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000009:adverse effects / Q000276:immunology; D014614:Vaccines, Synthetic / Q000009:adverse effects / Q000276:immunology
D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D018073:Haemophilus Vaccines; C061964:Haemophilus influenzae-type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine; D011135:Polysaccharides, Bacterial; D014614:Vaccines, Synthetic