Efficacy of a pneumococcal conjugate vaccine against acute otitis media

Background: Ear infections are a common cause of illness during the first t wo years of life. New conjugate vaccines may be able to prevent a substanti al portion of cases of acute otitis media caused by Streptococcus pneumonia e. Methods: We enrolled 1662 infants in a randomized, double-blind efficacy tr ial of a heptavalent pneumococcal polysaccharide conjugate vaccine in which the carrier protein is the nontoxic diphtheria-toxin analogue CRM197. The children received either the study vaccine or a hepatitis B vaccine as a co ntrol at 2, 4, 6, and 12 months of age. The clinical diagnosis of acute oti tis media was based on predefined criteria, and the bacteriologic diagnosis was based on a culture of middle-ear fluid obtained by myringotomy. Results: Of the children who were enrolled, 95.1 percent completed the tria l. With the pneumococcal vaccine, there were more local reactions than with the hepatitis B vaccine but fewer than with the combined whole-cell diphth eria-tetanus-pertussis and Haemophilus influenzae type b vaccine that was a dministered simultaneously. There were 2596 episodes of acute otitis media during the follow-up period between 6.5 and 24 months of age. The vaccine r educed the number of episodes of acute otitis media from any cause by 6 per cent (95 percent confidence interval, -4 to 16 percent [the negative number indicates a possible increase in the number of episodes]), culture-confirm ed pneumococcal episodes by 34 percent (95 percent confidence interval, 21 to 45 percent), and the number of episodes due to the serotypes contained i n the vaccine by 57 percent (95 percent confidence interval, 44 to 67 perce nt). The number of episodes attributed to serotypes that are cross-reactive with those in the vaccine was reduced by 51 percent, whereas the number of episodes due to all other serotypes increased by 33 percent. Conclusions: The heptavalent pneumococcal polysaccharide-CRM197 conjugate v accine is safe and efficacious in the prevention of acute otitis media caus ed by the serotypes included in the vaccine. (N Engl J Med 2001;344:403-9.) Copyright (C) 2001 Massachusetts Medical Society.