Risk factors for severe influenza A-related pneumonia in adult cohort, Mexico, 2013-14.

During the 2013-14 influenza season, we assessed characteristics of 102 adults with suspected influenza pneumonia in a hospital in Mexico; most were unvaccinated. More comorbidities and severity of illness were found than for patients admitted during the 2009-10 influenza pandemic. Vaccination policies should focus on risk factors.