Association between Patient Age and Influenza A Subtype during Influenza Outbreaks

The distribution of influenza A subtypes was studied in specimens recovered from patients in long-term care facility (LTCF) outbreaks and in non-LTCF outbreaks in Alberta, Canada, for 3 years before the influenza pandemic of 2009. We found that H3 but not H1 was associated with infection in older adults. Therefore, H3 was more commonly found than H1 in outbreaks in LTCFs. Infect Control Hosp Epidemiol 2010; 31(5):535-537