Acute otitis media is a common cause of illness in young children, has associated long-term effects and carries a considerable economic burden. Eskola and colleagues reported the results of a large, randomized, double-blind trial in Finland to test the ability of a heptavalent pneumococcal conjugate vaccine to prevent acute otitis media.

With parental consent, 55 percent of infants from smaller cities in Finland (population: 22,000 to 191,000) were enrolled in the study. Of these children, 831 were assigned to receive pneumococcal polysaccharide–CRM197 conjugate vaccine; the 831 infants in the control group were given hepatitis B vaccine. The children in both groups were followed for the occurrence of otitis media from the age of six months to two years. The diagnosis of otitis media was determined by specific predefined criteria. Myringotomy was accomplished in more than 90 percent of visits for acute otitis media, and the middle ear fluid obtained was cultured for the usual bacterial otitis pathogens (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella [Branhamella] catarrhalis).

The children who received the pneumococcal vaccine had, on average, 1.16 episodes of otitis media between the ages of six months and two years, whereas the children in the control group had 1.24 episodes, for a pneumococcal vaccine efficacy of 6 percent against acute otitis media from any cause. There was a shift in the flora causing the otitis media in the vaccine group, with a large reduction in infections caused by the pneumococcal serotypes included in the vaccine (down 57 percent) and an increase in the serotypes not covered in the vaccine (up 33 percent).

No harmful effects from the study vaccine were identified. The immunogenicity of the vaccine was good, with more than 80 percent of children demonstrating an appropriate increase in pneumococcal antibodies.

The authors concluded that the heptavalent pneumococcal conjugate vaccine was safe and effective for the prevention of acute otitis media.

editor's note: This large and well-designed trial essentially duplicates the results of the initial study performed in the United States, which showed an overall vaccine efficacy of 7 percent for reducing the number of cases of otitis media. How physicians will interpret the results is likely to vary widely. The skeptical reader will note that the 95 percent confidence interval for the demonstrated vaccine efficacy included zero (i.e., no benefit) and that the clinical significance of 1.16 versus 1.24 episodes of otitis media might be “underwhelming.” In addition, only 55 percent of eligible children were enrolled, which could lead to unaccounted-for selection biases.—b.z.