While it is almost a certainty that within the next few decades humanity will experience another influenza pandemic, it may not be caused by the avian influenza strain H5N1 that many scientists believe could be a prime candidate.

"We continue to be aroused and some nearly panicked by the threat of a flu pandemic caused by the avian influenza virus, H5N1. Is this anxiety justified? In the more than 15 years since it was first recognized, this bird flu virus has yet cause very much mortality in humans or evolve to be readily transmitted between people," says Bruce Levin, the Samuel Candler Dobbs Professor of Biology at Emory University.

Nevertheless, because of the high case mortality of humans infected with H5N1 (sometimes exceeding 90%), pandemic influenza caused by this avian virus has appropriately stimulated a great deal of research on the microbiology, immunology, pathology, virulence, epidemiology and evolution of influenza. It has also contributed to a renaissance of interest in the great influenza of 1918, says Levin.

"The next pandemic could well have the potential to kill as many or more people than that in 1918, but we are far better prepared to deal with the next influenza pandemic than we were that of 1918," says Levin.

Unlike now, in 1918:

* It was not clear that a virus was responsible for the pandemic

* There were no vaccines or even ways to develop vaccines to prevent the disease

* There were no antiviral drugs to mitigate the course of this disease and reduce the rate of transmission

* There were no antibiotics to treat, or vaccines to prevent, secondary bacterial infections that evidence suggests were the major cause of mortality in influenza patients.

This research was presented February 23, 2009 at the ASM Biodefense and Emerging Diseases Research Meeting in Baltimore, Maryland.