Haemophilusinfluenzae type b conjugate vaccine for preventing pneumonia in infants hospitalized for bronchiolitis: A case–control study

Abstract

Haemophilus influenzae type b (Hib) conjugate vaccine reduces the risk of pneumonia in infants. To determine the effect of Hib conjugate vaccine (HibCV) on the prevention of pneumonia as a complication among infants hospitalized for bronchiolitis. This record-based case-control study was conducted at The Children's Hospital "Dr. Ovidio Aliaga U" in La Paz, Bolivia during 2003 and 2004. Cases were infants hospitalized for bronchiolitis under 1 year of age who developed radiological pneumonia during hospitalization. Controls were patients who had good clinical progress without the use of antibiotics. Pneumonia was defined by alveolar consolidation on chest X-ray that justified the use of antibiotics. Eighty patients were studied (16 cases and 64 controls). Their median age was 4.5 months. Demographic and clinical features were similar in both groups, except for a higher proportion of vomiting (56.3% vs. 28.1%; p<0.05) in the case group. The percentage of unvaccinated infants was significantly higher in cases (68.8% vs. 26.6%; p<0.05) and the length of hospital stay longer (8.5+/-5.4 vs. 3.1+/-2.2 days; p<0.05). There was a strong association between unvaccinated infants and the occurrence of pneumonia as a complication (odds ratio 6.1, 95% confidence interval 1.8-20.1; p<0.01). Unvaccinated infants admitted for bronchiolitis have a higher risk of radiologically confirmed pneumonia. Larger studies are needed to validate these results and reconsider the burden of Hib infection among infants in less developed countries.