National impact of universal childhood immunization with pneumococcal conjugate vaccine on outpatient medical care visits in the United States.

BACKGROUND: Since introduction of the heptavalent pneumococcal conjugate vaccine in the United States in 2000, rates of invasive pneumococcal disease have declined. However, the national impact of heptavalent pneumococcal conjugate vaccine on pneumonia and otitis media remains unknown.

OBJECTIVES: We compared national rates of outpatient visits for pneumonia and otitis media in children before and after heptavalent pneumococcal conjugate vaccine introduction.

METHODS: Rates of ambulatory visits for pneumococcal and nonspecific pneumonia, otitis media, and other acute respiratory infections were compared before (1994-1999) and after (2002-2003) heptavalent pneumococcal conjugate vaccine introduction using the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey. To evaluate vaccine effects while accounting for temporal variability, ratios of pneumococcal-related disease rates in children < 2 years old (vaccine target population) and in children 3 to 6 years old (not routinely vaccinated) were evaluated using a Poisson regression analysis. For children < 2 years old, the differences between observed and expected rates were the estimated vaccine effects.

RESULTS: After the introduction of heptavalent pneumococcal conjugate vaccine, otitis media visit rates declined by 20% in children aged < 2 years. This decline represented 246 fewer otitis media visits per 1000 children aged < 2 years annually. There were no significant decreases in outpatient visit rates for pneumonia or other acute respiratory infections for children aged < 2 years.

CONCLUSIONS: After heptavalent pneumococcal conjugate vaccine introduction, national rates of otitis media visits declined significantly in children < 2 years old. Persistence of this trend will produce a significant reduction of the otitis media burden and further enhance the cost-effectiveness of heptavalent pneumococcal conjugate vaccine.