Written By Patrick Di Justo - Wired.com
At the height of the swine flu pandemic this spring, when the US Centers for Disease Control and Prevention was recommending that schools with cases of H1N1 be closed for 14 days and Mexico was still on lockdown, the epidemiology community already suspected the world wasn't ending. Why? The numbers came in: case fatality rate (how many infected people are dying) and replication rate (how many others an infected person will
transmit the illness to — "R-zero," in disease-speak). H1N1 had an RØ of about 1.3, high enough to spread the virus but low enough that a strong isolation program could break its back. Its case fatality rate was a wussy 1.9 percent in Mexico and 0.1 percent worldwide. By comparison, the 1918 Spanish flu had an RØ of 2.7 and a case fatality rate of up to 5 percent, making it far more deadly. A real apocalypse, like the killer flu in The Stand — Stephen King's opus of epidemiologic eschatology — would be off the chart, with an RØ of 5 to 6 and a case fatality rate of 99 percent. So, don't panic ... unless H1N1 surges this fall. Where did we leave that hand sanitizer, again?
Why It Was Scary
Instead of opportunistically killing only children and the elderly, the 1918 Spanish flu killed many young adults. As of May 27, H1N1 was following the same pattern in Mexico. That's a sign of a disease to fear.
Death and Illness
Showing illnesses and deaths on a linear graph makes clear the runaway exponential curve of Captain Trips and the simulated H1N1, and the more limited growth of real-life swine flu. Viruses spread exponentially as long as there is something to grow on (i.e. non-immune carriers) and a way to spread (i.e., no quarantine).
World-Wide Projections
This report demonstrates the spread of this iteration of swine flu worldwide if it had the same characteristics as the 1918 version in terms of RØ and mortality, but included air travel among the infected. (Compare it with the real-life H1N1 map from GLEaM.)
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