RI influenza surveillance summary 2012-2013.

The United States experienced a severe and prolonged influenza season between October 2012 and April 2013. Influenza A (H3N2), influenza A (H1N1), and influenza B viruses co-circulated. Compared with recent influenza seasons, this season had a higher percentage of outpatient and Emergency Department (ED) visits for influenza-like illness (ILI), higher rates of hospitalizations, and more deaths.1 Rhode Island was no exception to this national trend. The circulating strains of influenza were a good match to the vaccine strains, but vaccine effectiveness was observed to be poor. Vaccine effectiveness (adjusted for age, site, race/ ethnicity, self-rated health, and days from illness onset to enrollment) against influenza A and B virus infections associated with medically attended acute respiratory illness was 56%.2 The circulating influenza A strains were sensitive to oseltamivir and zanamivir.