AbstractObjective:To characterize risk factors for invasive pneumococcal infection in a nursing home outbreak.Design:Outbreak investigation, case-control study.Setting:A 114-bed nursing home in New Jersey.Participants:Case-patients were nursing home residents hospitalized with febrile respiratory illness and radiographic findings consistent with pneumonia, and either sputum specimens positive for diplococci or blood cultures positive for Streptococcus pneumoniae, with illness onset during April 3-24, 2001. Control-patients were selected randomly from remaining residents without respiratory symptoms.Methods:Chart reviews were performed for case-patients and control-patients. Serotyping and susceptibility testing were performed on S. pneumoniae isolates. Long-term-care facilities (LTCFs) were surveyed to assess compliance with a state regulation mandating pneumococcal vaccination of residents 65 years and older.Results:Nine case-patients were identified, with a median age of 86 years (range, 78 to 100 years). The median age of control-patients was 86 years (range, 58 to 95 years). No case-patients versus 9 (50%) control-patients received pneumococcal vaccine before the outbreak (OR, 0; CI95, 0–0.7). Recent antibiotic use, pneumonia history, and physical functioning were not associated with illness. Illness attack rate was 16% among all unvaccinated residents versus 0 among vaccinated residents. S. pneumoniae serotype 14, included in pneumococcal vaccine, was isolated from blood cultures of 7 case-patients. Of 361 LTCFs (42%) that replied to the survey, 28 (8%) were not complying with state immunization regulations.Conclusions:This outbreak occurred in an LTCF with low vaccine coverage. Implementing standing order programs, enforcing regulations, documenting vaccinations, and providing education might increase coverage among nursing home residents.