The ability of influenza virus to adapt to various species and evade natural immunity makes the ubiquitous pathogen particularly difficult to eradicate. Annual reformulation of influenza vaccines is costly and time-consuming and has varying efficacy against influenza virus strains. Therefore, worldwide efforts aim to develop a universal influenza vaccine to prevent potential healthcare emergencies such as pandemic influenza threats, such as the 1918 Spanish Flu and pandemic Swine Flu of 2009. Efficacy of a universal influenza vaccine must overcome current challenges with subtype diversity, antigenic drift, and adequately protect against emerging reassortants from both environmental and agricultural sources. Furthermore, the manufacturing and production of vaccines largely influence the effectiveness of a vaccine and technological advancements may soon rival current vaccine strategies. This review discusses the evolution and diversity of influenza viruses, how viral glycoprotein hemagglutinin plays a dominant role in influenza surveillance and assessment of protection and compares the methodologies of current and upcoming vaccine options. While the obstacles remain daunting, growing knowledge of influenza evolution and immunity may lead to more viable candidates that protect against broader varieties of influenza viruses and help prevent future international health crises.
Part of the book: Steps Forwards in Diagnosing and Controlling Influenza