05 were considered significant. During the 8 influenza seasons, 4996 adults with acute respiratory illness seeking medical care were enrolled. Influenza infection was laboratory confirmed for 1393 persons; 1020 (73%) had type A infection, 369 (26%) had type B infection, and 4 (<1%) were positive for both type A and B. Most (84%) influenza A infections were H3N2 subtype, followed by H1N1 (10%) and H1N1pdm09 (6%). The number of influenza A positive study participants ranged from 18

in the 2005–06 season to 356 in the 2007–08 season. The number of influenza B positive study participants ranged from 5 in the 2006–07 season to 144 in the 2007–08 season. Among persons with laboratory confirmed influenza and known vaccination status,

583 (42%) were males, 540 (39%) had at least one high risk condition, 316 (23%) TSA HDAC were prescribed antiviral medications, and 31 (2%) were enrolled after admission to the hospital. The proportion vaccinated differed with respect to age, gender, and presence of high risk conditions (Table 1). In particular, influenza vaccination was more common in older adults and women. The median age was 55 years [interquartile range (IQR): 41, 69] among adults who were vaccinated and 41 years (IQR: 30, 52) among adults who were not vaccinated (p < 0.001). Vaccination was also more common among persons with cancer, cardiovascular disease, diabetes, pulmonary disorders, and other high risk conditions selleck chemical compared to those without these high risk conditions. Similar patterns were observed when examined by influenza type. Seventy-nine patients with laboratory confirmed influenza were admitted to the hospital within 14 days of symptom onset: 62 (6%) of 1020 with influenza A and 17 (5%) of 369 with influenza B. The median time from symptom onset to hospital admission was 3 days (IQR: 2–5 days). Seventy (89%) had discharge diagnoses

codes that were consistent with an acute respiratory illness or exacerbation of chronic pulmonary disease. Among hospitalized Rolziracetam patients, those who were older were more likely to be vaccinated compared to those aged 20–49 years and those with a cardiovascular high risk condition were more likely to be vaccinated compared to those without a cardiovascular high risk condition (Table 2). Vaccination status among hospitalized patients was not associated with gender or the other high risk conditions examined. Among patients with laboratory confirmed influenza, influenza vaccination was not associated with a decreased risk of hospitalization following onset overall or by influenza type (Table 3). The propensity score adjusted odd ratio of hospitalization for vaccinated compared to unvaccinated patients was 1.08 (95% CI: 0.62, 1.88), 1.35 (95% CI: 0.71, 2.57), and 0.67 (95% CI: 0.21, 2.15) overall, for type A infection, and for type B infection, respectively.