%0 Journal Article %T Passive Broad-Spectrum Influenza Immunoprophylaxis %A Cassandra M. Berry %A William J. Penhale %A Mark Y. Sangster %J Influenza Research and Treatment %D 2014 %I Hindawi Publishing Corporation %R 10.1155/2014/267594 %X Influenza is a perennial problem affecting millions of people annually with the everpresent threat of devastating pandemics. Active prophylaxis by vaccination against influenza virus is currently the main countermeasure supplemented with antivirals. However, disadvantages of this strategy include the impact of antigenic drift, necessitating constant updating of vaccine strain composition, and emerging antiviral drug resistance. The development of other options for influenza prophylaxis, particularly with broad acting agents able to provide protection in the period between the onset of a pandemic and the development of a strain specific vaccine, is of great interest. Exploitation of broad-spectrum mediators could provide barricade protection in the early critical phase of influenza virus outbreaks. Passive immunity has the potential to provide immediate antiviral effects, inhibiting virus replication, reducing virus shedding, and thereby protecting vulnerable populations in the event of an impending influenza pandemic. Here, we review passive broad-spectrum influenza prophylaxis options with a focus on harnessing natural host defenses, including interferons and antibodies. 1. Introduction Seasonal influenza causes serious disease burden, particularly in children and the elderly, with the need to develop annual vaccines based on predicted circulating strains due to antigenic drift of the virus. Furthermore, newly emerging novel influenza A viruses pose a significant threat of a pandemic with potentially devastating consequences [1]. Moreover, as pandemic strain vaccines require time for development and deployment, virus replication and spread are initially unchecked allowing the outbreak to gain momentum. Currently, vaccines and antivirals are used for control of influenza but emerging virus resistance to these measures presents limitations. Furthermore, as antiviral drugs could not be stockpiled in sufficient amounts for global supply, alternative control measures need to be urgently considered. A potential solution lies in the development of a universal vaccine based on conserved viral epitopes that induces cross-reactive antibodies that neutralize variant viruses from within a subtype and protects against heterologous viruses. Therefore, whilst existing vaccines are inadequate for cross protection and a universal vaccine may be difficult to achieve, it is both pertinent and timely to consider other possible broad-spectrum options, particularly as different virus subtypes not previously experienced by humans are emerging and have pandemic potential. In %U http://www.hindawi.com/journals/irt/2014/267594/