Flu vaccine may be most effective in patients not vaccinated in past 5 years

Influenza vaccination appears to confer protection against influenza infection regardless of a patient’s vaccination history, according to recent findings. The vaccine appears to offer the greatest protection, however, to patients who were not vaccinated within the previous 5 years, researchers wrote in Clinical Infectious Diseases. In the observational study conducted across eight influenza seasons, researchers evaluated vaccine effectiveness in a cohort of 7,315 community residents within a 14-ZIP code area near Marshfield, Wis. The study was conducted between the 2004-2005 and the 2012-2013 influenza seasons. Participants in the 2004-2005 through 2006-2007 portion of the study period were limited to those for whom vaccination was recommended based on age or other high-risk status. From 2007-2008 onward, the study population was expanded to include all residents of the community aged 9 years and older. Patients were recruited for each influenza season during clinical examinations for acute respiratory illness. They were interviewed about their symptoms, and...