Effects of previous episodes of influenza and vaccination in preventing laboratory-confirmed influenza in Navarre, Spain, 2013/14 season.

Effects of previous episodes of influenza and vaccination in preventing laboratory-confirmed influenza in Navarre, Spain, 2013/14 season. Euro Surveill. 2016 Jun 2;20(22) Authors: Castilla J, Navascués A, Fernández-Alonso M, Reina G, Albéniz E, Pozo F, Álvarez N, Martínez-Baz I, Guevara M, García-Cenoz M, Irisarri F, Casado I, Ezpeleta C, Primary Health Care Sentinel Network and Network for Influenza Surveillance in Hospitals of Navarra Abstract We estimated whether previous episodes of influenza and trivalent influenza vaccination prevented laboratory-confirmed influenza in Navarre, Spain, in season 2013/14. Patients with medically-attended influenza-like illness (MA-ILI) in hospitals (n = 645) and primary healthcare (n = 525) were included. We compared 589 influenza cases and 581 negative controls. MA-ILI related to a specific virus subtype in the previous five seasons was defined as a laboratory-confirmed influenza infection with the same virus subtype or MA-ILI during weeks when more than 25% of swabs were positive for this subtype. Persons with previous MA-ILI had 30% (95% confidence interval (CI): -7 to 54) lower risk of MA-ILI, and those with previous MA-ILI related to A(H1N1)pdm09 or A(H3N2) virus, had a, respectively, 63% (95% CI: 16-84) and 65% (95% CI: 13-86) lower risk of new laboratory-confirmed influenza by the same subtype. Overall adjusted vaccine effectiveness in preventing laboratory-confirmed influenz...
Source: Euro Surveill - Category: Infectious Diseases Authors: Tags: Euro Surveill Source Type: research