Friday, May 1, 2009

Daily Flu-ness

(HHS/CDC/DHS Webcast, sourced at

Veratect Twitter Feed
Google US Flu Trend
Google Mexico Flu Tend (experimental)
(Illustration: Periods, Phases, Stages, and Intervals; from Flu Wiki)

(Illustration: Pandemic Influenza Phases; World Health Organization)

Current WHO pandemic phase: 5
Laboratory confirmed cases worldwide: 367 in 13 countries
Laboratory confirmed deaths worldwide: 10 in two countries
Official designation: influenza A(H1N1)
Laboratory confirmed cases in US: 141
Laboratory confirmed deaths in US: 1

International efforts to contain influenza A(H1N1) have failed. That's not surprising and it's not a fatal error. International travel is simply too widespread, too cheap, and too fast to successfully contain a disease with several days of asymptomatic or minimally symptomatic incubation like the flu. Containment was always a pipe dream.

As we approach the brink of a pandemic, there are important unknowns: how many people actually have A(H1N1)?; what is the mortality rate?; and are we dealing with a single strain? I'm sure there are others. If we are seeing 10 deaths out of 367 cases that's one thing but 10 deaths out of 10,000 cases is something very different. The number of cases and number of deaths together give us the mortality rate. A mortality rate of 0.1% is much less scary than a mortality rate of 2.5%. A single strain means that we can build a vaccine relatively quickly and be reasonably confident that it will do the job, while multiple strains lead to concern that we may see multiple waves of contagion with limited immunity conferred by surviving one wave.

At the moment, this proto-pandemic is far less lethal than a typical flu season (in the US: November through March) which hospitalizes more than 200,000 and kills 36,000 in the US. Whether A(H1N1) becomes a pandemic or not, it's entirely possible that it will remain far less lethal than the typical flu season. "Pandemic" doesn't mean "lots of people die" -- it means widespread cases and transmission. Widespread cases and transmission means the possibility of lots of people dying, and the word "pandemic" brings up images of The Hot Zone and Outbreak and Ebola Zaire killing people in the streets of Washington DC and on Maple Street, Anytown.

(Video: The Twilight Zone, The Monsters are Due on Maple Street)

We're not there yet, and we may never be there. Everyone fears a repeat of the biggest pandemic we know about: 1918-1920 (millions of deaths -- 5, 10, 50, or 100 million worldwide -- from H1N1 flu). We may have a relatively mild pandemic like 1959 (100,000 deaths worldwide from H2N2 flu) or 1968 (700,000 deaths worldwide from H3N2 flu). We are better prepared for a pandemic than ever before. We have better diagnostic technology (including genomic typing of flu strains) and vaccine design technology than ever before. We're still limited to a 6-month growth lead time in creating large quantities of a vaccine, though. And we know that there are other strains out there which may be more dangerous.

Even without a dangerous pandemic, our preparation and response carries a price. Accounting for risk and preparing for it, responding to it, always does. When this is all over, if it's mild, we can expect some people to decry the cost of our response -- maybe even if it's disastrous. But preparing and responding to risk is something that we do as a civilized society (or a network of civilized societies sharing our planet together). I predict that the people who complain about cost of response will tend to the authoritarian and conservative.

Other Stories
Q's without A's: 6 mysteries about swine flu
How swine flu virus hopscotched the globe
Swine flu may be less potent than first feared

Oh, and do you know that there were no viruses or bacteria until Adam & Eve ate the apple?