H1N1 flu: Maybe 1918 doesn't teach us much
An oft-stated fear about the pandemic H1N1 flu is the possibility that it is behaving like the deadly 1918 flu -- showing its face in a mild form in the spring of 1918 before swooping back, somehow mutated to become more deadly, to kill countless more in the latter part of 1918 and in 1919.
Is that what the 1918 flu really did? And is that how dangerous pandemic flus generally behave, making the fairly mild face of H1N1 we've seen so far portend something sinister for the winter?
We really don't know, say influenza experts Dr. David Morens and Dr. Jeffery Taubenberger of the National Institute of Allergy and Infectious Diseases in a commentary in this week's Journal of the American Medical Assn.
From their analysis of the 1918 flu, they conclude that neither the "spring wave" hypothesis nor the idea that the virus mutated in a nasty fashion somewhere along the way are properly established. Though Taubenberger's team has managed to analyze 1918 flu samples, they haven't been able to find spring wave samples with which to do comparisons.
The two scientists also looked at 14 other pandemics that took place over the last 500 years. Some were clearly more severe than others, they write. And the two other pandemics that occurred this last century -- in 1957 and 1968 -- didn't appear to become more lethal as time wore on.
They see reason to hope that this pandemic won't be among the worst, based on the observations that the H1N1 pandemic virus doesn't seem especially easily transmissible, plus it looks like people of older ages may have some immunity to it, probably based on past exposure to some similar-enough virus.
Neither Morens nor Taubenberger are saying, "Hey, don't worry about H1N1" -- they stress that surveillance and emergency preparedness are crucial. And that's because -- as they make clear -- no obvious pattern emerges from studying any of the known past pandemics. They end their article with a quote adapted from 19th century philosopher Soren Kierkegaard. "Influenza epidemics are lived forward and understood backward."
(Kierkegaard's quote was, "Life can only be understood backwards; but it must be lived forwards.")
You can't read the JAMA article without paying, but here's an interesting article on the topic posted on a listserv that infectious disease experts like to read, Promed mail. Sending you there instead of elsewhere on the Web because Promed is a treasure trove for anyone interested in diseases infecting people and animals around the world.