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Posted by on Apr 30, 2009 in At TMV, Science & Technology | 4 comments

Deconstructing Swine Flu Mania

I don’t know about you, but I felt a little shiver along my spine when I heard on Wednesday that the World Health Organization had raised its H1N1 swine flu threat level to five, on a scale of one-to-six. I didn’t know what that meant, exactly. But news reports linking this threat level with the 1968 Hong Kong flu and the word “pandemic” were shaking my belief that the U.S. media were on one of their normal echo-chamber benders.

Today WHO reported that 11 countries have “officially reported 257 cases of influenza A (H1N1) infection.” In the U.S., we have 109 laboratory-confirmed human cases and one death. In Mexico, there are 97 confirmed human cases and seven deaths.

Adding to my unease: I just flew cross-country with over-full aircraft (babes in arms = more individuals than seats). But it was thinking about that trip that gave rise to this insight: given the growth in global travel, rapid spread of disease (“going viral”) should be increasing.

So I went to the source, and here’s what I found. Maybe it will help set your mind at ease. (Or maybe not.)

What Does A Phase 5 Threat Mean?
Learning the answer to this question reinforced my wonder that global travel hasn’t triggered such a threat before (that I can remember). From WHO:

Phase 5 is characterized by human-to-human spread of the virus into at least two countries in one WHO region.

Oh. Well, the Mexico-U.S. connection (we share a border, remember) certainly makes this threat level less scary.

One reason that I don’t remember hearing about this before may be that this threat level schema is less than 10 years old. (I say “may” because the claim is not sourced.)

A Phase 6 threat seems imminent, given today’s WHO report. And given global air traffic, even in a recession, this upgrade seems likely to me. When that happens, we will officially have a “pandemic.”

What Is A Pandemic?
From WHO: “An influenza pandemic occurs when a new influenza virus appears against which the human population has no immunity, resulting in epidemics worldwide with enormous numbers of deaths and illness.”

That word “enormous” gives one pause, doesn’t it? The last big pandemic was 1968, when the Hong Kong flu killed an estimated 1 million worldwide. The granddaddy — the one that I think of when I hear the word — was in 1918-1919; the Spanish Flu (a variant of H1N1) led to an estimated 40–50 million global deaths.

However, even WHO doesn’t anticipate another epidemic like we had in 1918: “Current epidemiological models project that a pandemic could result in 2 to 7.4 million deaths globally.”

Let’s put these numbers in context. In 1918, the world population was about 1.8 billion. That means that the H1N1 virus swine flu killed about 3 percent of the world’s population. According to the U.S. archives, more than 25 percent of the U.S. population experienced the flu, however.

Today, the world population is approximately 6.7 billion. Taking the worst-case WHO estimate, as much as 0.1 percent of the world’s population is at risk of death if this flu indeed becomes a pandemic. In other words, it still sounds to me like the risk is small.

What About Drugs?
President Obama called on Congress to allocate $1.5 billion (in other words, to borrow another $1.5 billion) to, among other things, supplement antiviral stockpiles and begin preparing a vaccine.

Sounds good, doesn’t it? Well, think again. Here’s Maggie Koerth-Baker on vaccines:

[T]he lag time on vaccine production is pretty gnarly. We’re talking 3-to-6 months before anything can get out the door, and that’s with development and production being fast-tracked. Because flu viruses tend to pretty quick on the mutation draw, the “wild” virus will likely be different from the one the vaccine is modeled on by the time it comes out…. It may not prevent illness altogether, but the illness you get might be more mild that what you’d have come down with otherwise. That said, there’s also a distinct possibility that, by the time a vaccine is out, H1N1 swine flu won’t be a problem anymore.

Of course, no one who holds elected office is going to vote no on spending money to try to develop a vaccine for H1N1 swine flu.

What Is H1N1?
I find it intriguing that in 2005, WHO was worried about the possibility of a pandemic, but not because of H1N1 (pdf). Their concern was focused on H5N1, avian flu. This, I remember, because the center of that storm was Asia and I live in greater Seattle. There are no vaccines for avian flu, and it is transmitted from bird to human.

H1N1, on the other hand, is linked to pigs (hence the nickname “swine flu”) and the 1918-1919 pandemic. Unlike avian flu, H1N1 has mutated which makes it possible to be transmitted from human-to-human. It is a sub-sub-category of Type “A” influenza, which includes “seasonal flu.”

This CDC chart shows us that Type A is the most common “flu bug” in the U.S. Moreover, as many as 250,000 to 500,000 people die (worldwide) after contracting the flu in a “normal” year. Most of us have some immunity to “seasonal flu” and/or we take a flu shot to help prevent the disease.

“The flu” is not a cold and it’s not intestinal (“stomach flu”). It is a respiratory disease, which helps explain why its victims are usually elderly or children — their immune systems are at higher risk of death after becoming ill.

Interestingly, in 2008 the U.S. significantly exceeded the “epidemic” threshold for pneumonia and seasonal influenza based on mortality statistics. However, a quick Google search yields no media panic; it does, however, yield articles criticizing the country’s influenza preparedness.

So What Can You Do?
The basics: cover your mouth/nose when you cough or sneeze. Wash your hands regularly, with soap and hot water, especially if you have coughed or sneezed. Keep your hands away from your face. And stay home if you start to feel feverish!

Here are some “check-regularly” sources, absent media hype:

Added: Also read this excellent statistical analysis by TMV writer Mikkel Fishman.