Impact of PCV7 on invasive pneumococcal disease among children younger than 5 years: a population-based study.

We examined the impact of the heptavalent pneumococcal conjugate vaccine (PCV7) on hospital discharge rates for invasive pneumococcal disease among Michigan children younger than 5 years old. After the introduction of PCV7, the hospital discharge rate for children younger than 1 years old was significantly lower than before introduction. We correlated the decreased rates with the introduction and rapid uptake of PCV7. Lack of change in the hospital discharge rates for other age groups likely represents a slower uptake of PCV7 compared with that for children aged younger than 1 year.