Incidence of Medically Attended Respiratory Syncytial Virus and Influenza Illnesses in Children 6–59 Months Old During Four Seasons

Simpson, Melissa D.; Kieke, Burney A.; Sundaram, Maria E.; McClure, David L.; Meece, Jennifer K.; Sifakis, Frangiscos; Gasser, Robert A.; Belongia, Edward A.

This study was a secondary analysis of samples and data from children with ARI who were enrolled and tested for influenza to estimate vaccine effectiveness; details of these studies have been published [10] [11] [12] . In brief, patients age ≥6 months with MAARI were enrolled from the population of communitydwelling individuals living in the central region of the Marshfield Epidemiologic Study Area (MESA), a dynamic, population-based cohort of approximately 54 000 residents living in 14 zip codes surrounding Marshfield, Wisconsin. Nearly all MESA residents receive their medical care from Marshfield Clinic, an integrated, multispecialty healthcare system serving the MESA population. The Marshfield Clinic electronic medical record captures approximately 93% of outpatient visits, 93% of hospital discharges, and 99% of deaths for the MESA population [13, 14] . This study focused on children living in MESA who were 6-59 months old at the start of each influenza season. Although data on race and ethnicity were not collected during all study seasons, US Census data from 2010 indicate that 94% of Marshfield residents are white, non-Hispanic.