Influenza Exposure May Lead to Heightened Risk in Future Pandemics

Throughout the past century there have been at least 5 pandemics related to the influenza A virus and a new data analysis published in mBio by the American Society for Microbiology, suggests that individuals born at the time of a pandemic are more susceptible to death in future pandemics.

This new finding is contrary to the widely accepted idea that exposure to influenza A viruses typically creates a defense against strains of influenza.

Matthew Miller, PhD, senior author of the paper, assistant professor in the Department of Biochemistry and Biomedical Sciences at McMaster University, and senior researcher with its Michael G. DeGroote Institute of Infectious Disease Research, told EurekAlert! that the enhanced vulnerability has been poorly understood in the infectious disease community and that future studies should focus on determining the factors that are responsible for the heightened susceptibility.

Dr. Miller and teams from McMaster University and the Université de Montréal analyzed influenza data from October 1997 to July 2014 collected from the United States and Mexico. The results found that individuals who were born just prior to the 1957 H2N2 Asian Flu pandemic had higher mortality rates during the 2009 H1N1 Swine Flu Pandemic and the 2013-2014 H1N1 outbreak.

Consistent findings were reported amongst the data collected in previous pandemics. Those exposed to the influenza virus during the 1890 pandemic had higher death rates in the 1918 pandemic, just as those affected in 1918 had higher death rates during the 1968 pandemic.

“We suggest the phenomenon of 1918 is not unique,” Miller told EurekAlert!. “We believe that exposure to pandemic influenza early in life is a risk factor for mortality during subsequent cross-strain pandemics.”

The findings of this study suggest that a solution would be a vaccine that protects against multiple strains of influenza. William Schaffner, MD, medical director of the National Foundation for Infectious Diseases, recently discussed if it is possible to develop a universal flu vaccine with Contagion^®.

But before any new vaccines can be developed to prevent the increased susceptibility to individuals exposed to multiple pandemics, researchers must pinpoint exactly what is causing the heightened risk among those previously affected.