Severe pneumococcal pneumonia in previously health children: the role of preceding influenza infection. Clin. infect

An outbreak of severe pneumococcal pneumonia among children occurred in Iowa from November 1995 through January 1996. An associated outbreak of in¯uenza disease was pre-dominantly caused by in¯uenza A (H1N1) for the ®rst time since 1989. We conducted a case-control study to determine whether preceding in¯uenza infection was directly associated with pneumococcal illness. We identi®ed 13 children with severe pneumococcal pneumonia. Patients were more likely than control subjects to report experiencing an in¯uenza-like illness in the 7±28 days preceding admission (matched odds ratio [OR], 12.4; 95 % con®dence interval [CI], 1.7±306). Likewise, family members of patients were more likely than those of control subjects to report experiencing an in¯uenza-like illness in the 28 days preceding their admission date (OR, 2.6; 95 % CI, 1.0±6.3). Patients were more likely than control subjects to have a positive in¯uenza A (H1N1) convalescent serology (matched OR, 3.7; 95 % CI, 1.0±18.1). This study provides direct and indirect evidence that in¯uenza infection led to severe pneumococcal pneumonia among these children. Prevention of pneumococcal disease should be included among the potential bene®ts of in¯uenza vaccination. In¯uenza infection is a commonly cited risk factor for sec