Community-acquired respiratory viruses and co-infection among patients of Ontario sentinel practices, April 2009 to February 2010.

Background: Respiratory viruses are known to cocirculate but this has not been described in detail during an influenza pandemic.

Objectives: To describe respiratory viruses, including co-infection and associated attributes such as age, sex or comorbidity, in patients presenting with influenza-like illness to a community sentinel network, during the pandemic A(H1N1)pdm09 in Ontario, Canada.

Methods: Respiratory samples and epidemiologic details were collected from 1018 patients with influenza-like illness as part of respiratory virus surveillance and a multiprovincial case-control study of influenza vaccine effectiveness.