Few Asian countries have introduced Haemophilus influenzae type b (Hib) conjugate vaccine because of its cost and uncertainty regarding disease burden.
To estimate the effectiveness of Hib conjugate vaccine in preventing pneumonia and meningitis in children age <2 years, an incident case–control study was conducted in a birth cohort of about 68,000 infants in Dhaka city, Bangladesh. DPT vaccine was systematically replaced by a combined Hib-DPT vaccine in selected immunization centers of the study area. Four matched community- and 2 hospital-controls were randomly selected for each confirmed case of pneumonia and meningitis from the study area.
About 35% of the infants received each of the 3 doses of Hib-DPT vaccine. There were 2679 children who had a chest roentgenogram. For 475 children, a radiologist and a pediatrician independently identified substantial alveolar consolidation. Following at least 2 doses of Hib vaccine, the preventable fractions [95% confidence intervals (CI)] using community and hospital controls were 17% (−10% to 38%) and 35% (13% to 52%) respectively. Of these 475 cases, 2 radiologists with the World Health Organization concurred with the findings for 343 patients, yielding preventable fractions of 34% (6% to 53%) and 44% (20% to 61%). Fifteen confirmed Hib meningitis cases were identified; the preventable fractions (95% CI) using community and hospital controls, respectively, were 89% (28% to 100%) and 93% (53% to 100%).
The study documented that significant fractions of pneumonia and meningitis in Bangladeshi children age <2 years can be prevented by the Hib conjugate vaccine.
From the *Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; †Child Health Program, ICDDR,B, Dhaka, Bangladesh; ‡Department of Microbiology, Dhaka Shishu Hospital, Shamoli, Dhaka, Bangladesh; §International Maternal and Child Health, Uppsala University, Uppsala, Sweden; ∥Association Pour l'Aide a la Medicine Preventive, Paris, France.
Accepted for publication March 22, 2007.
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