RT Book, Section A1 Sutton, S. Scott A1 Bookstaver, P. Brandon A2 Sutton, S. Scott SR Print(0) ID 7252600 T1 Chapter 30. Influenza T2 McGraw-Hill's NAPLEX® Review Guide YR 2011 FD 2011 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-175562-7 LK accesspharmacy.mhmedical.com/content.aspx?aid=7252600 RD 2024/03/29 AB Influenza causes significant morbidity and mortality, particularly among young children and the elderly. Seasonal influenza epidemics result in 25 to 50 million influenza cases, approximately 200,000 hospitalizations, and more than 30,000 deaths each year in the United States.1-3 Influenza infection can occur at any time during the year with the highest rates of illness occurring between December and March.4 Influenza A and B are the two types of influenza viruses that cause disease in humans. Influenza A viruses are categorized into different subtypes based upon presence of two surface antigens—hemagglutinin and neuraminidase.1-2 Immunity to influenza virus occurs as a result of the development of antibody directed at the surface antigens.