Seasonal Influenza A H1N1pdm09 Virus and Severe Outcomes: A Reason for Broader Vaccination in Non-Elderly, At-Risk People

Abstract

Hospitalized patients with influenza A(H1N1) were more than twice as likely to have severe influenza. They were younger and most had not received the vaccine. Our findings suggest that seasonal influenza A(H1N1) maintains some features of pandemic viruses, and recommend wider use of vaccination in younger adult high-risk patients.