There have been considerable advances in medical technology and scientific knowledge in dealing with influenza since the early 1900s. Prevention strategies involving annual influenza vaccination and a global prevention infrastructure are in place. Still, the influenza virus continues to pose novel challenges by donning new disguises that manage to outwit our immune system. While the planning for the next influenza pandemic was centered on the possible emergence of a new influenza A subtype of avian origin, the first pandemic of the 21st century was caused by a reassortant swine influenza virus of the same subtype as the circulating human seasonal influenza A. Even though a century separates the emergence of the two viruses, the HAs of the 1918 pandemic virus and A(H1N1)pdm09 virus have marked similarities. These two pandemics teach us a valuable lesson: that influenza pandemics are unpredictable in nature and may often deliver surprises.
Extensive globalization and high rates of air travel facilitate the rapid spread of influenza virus, as happened with A(H1N1)pdm09. However, in 1918, when global air travel was not as advanced, the virus was still transmitted rapidly, spreading around the world within a few weeks. Even after a century, mysteries surrounding the 1918 pandemic have not been fully solved and new pandemics continue to evolve. These pandemics expose the fact that there are gaps that need to be addressed in influenza surveillance in humans and other animals. A significant fraction of the population is now expected to be protected from A/H1N1 influenza through natural exposure or vaccination. There is also potential for the emergence of a drift variant of A(H1N1)pdm09 and/or emerging age patterns that are often witnessed during post-pandemic periods. We must therefore remain vigilant and continue to monitor the epidemiology and health burden of the A/H1N1 influenza virus. Animal health workers and human health workers should work in collaboration to achieve heightened surveillance in swine and other animals. A multinational comparison of the epidemiology of pandemic and post-pandemic waves would offer insights on the long-term transmission dynamics of the pandemic viruses, thus helping to formulate control strategies.
There is an urgent need to develop methods that reduce the time gap between the detection of a virus and wide availability of the vaccine. The current shortcomings lies in our dependence on the development of egg-based vaccines, which is inconsistent and slow. Furthermore, large-scale sequencing, bioinformatics analysis and working with recombinant viruses to predict the emergence of new pandemics is the need of the hour.
Future Virology. 2013;8(4):335-342. © 2013 Future Medicine Ltd.