Underlying conditions in children with invasive pneumococcal disease in the conjugate vaccine era.

We analyzed characteristics of invasive pneumococcal disease cases occurring in Massachusetts after the introduction and use of conjugate vaccine by underlying risk. Among 578 cases with sufficient information, 16% had high-risk or presumed high-risk conditions (HR/PHR), 3% had asthma, and 80% had no known risk (NKR). The most common HR/PHR conditions were disorders associated with immunosuppression. HR/PHR cases tended to be older and were more likely to be hospitalized than were children with NKR. Children with asthma presented with pneumonia more often than children with NKR.