Lack of efficacy of Haemophilus b polysaccharide vaccine in Minnesota
M. T. Osterholm, J. H. Rambeck, K. E. White, J. L. Jacobs, L. M. Pierson, J. D. Neaton, C. W. Hedberg, K. L. MacDonald and D. M. Granoff
Acute Disease Epidemiology Section, Minnesota Department of Health, Minneapolis 55440.
We evaluated the efficacy of Haemophilus b polysaccharide vaccine in
children in Minnesota using a case-control study. The vaccine became
available in Minnesota in August 1985. During the subsequent 28 months, 88
cases of invasive H influenzae type b disease were identified in children
24 to 71 months of age, the group targeted for vaccination. Of the 88
cases, 36 (41%) occurred in vaccinated children. Fifty-eight (33%) of 176
controls were vaccinated during a similar period. The vaccine's protective
efficacy for children with any history of vaccination was -58% (95%
confidence interval = -204% to 18%). The vaccine's protective efficacy for
children who were most likely to be protected by vaccination was -55% (95%
confidence interval = -238% to 29%). Our results indicate that vaccination
with Haemophilus b polysaccharide vaccine had no effect in preventing H
influenzae type b disease in Minnesota children.
