The prospects and challenges of universal vaccines for influenza

• A new generation of broadly cross-protective influenza vaccines is on the horizon.
• These vaccines may ameliorate disease rather than prevent infection.
• The HA stem, M2, NP, and M proteins of the virus are the preferred targets.
• Innovative methods to enhance vaccine immunogenicity and delivery will be needed.

Vaccination is the most effective way to reduce the impact of epidemic as well as pandemic influenza. However, the licensed inactivated influenza vaccine induces strain-specific immunity and must be updated annually. When novel viruses appear, matched vaccines are not likely to be available in time for the first wave of a pandemic. Yet, the enormous diversity of influenza A viruses in nature makes it impossible to predict which subtype or strain will cause the next pandemic. Several recent scientific advances have generated renewed enthusiasm and hope for universal vaccines that will induce broad protection from a range of influenza viruses.