White Coat Underground

Swine flu—don’t panic

So far, it looks like the US Gov’t is on top of this one. If you’re interested in following along with the story, I strongly suggest following the Effect Measure blog. The writers know their stuff, and so far, government websites aren’t all that much health.

Some basics:

As you remember, the flu virus changes over time due to “antigenic drift” and we need to make new vaccines every year. Sometimes, often due to multiple strains co-infecting the same animal, the influenza genome undergoes a more dramatic change called “antigenic shift”. Influenza A is commonly found in birds, pigs, and humans. If strains from different species co-infect say, a pig, the genes can undergo some mixing (to be completely un-technical) producing an antigenically new strain which may then move back to other animals.

In the current case, it appears as if a swine flu virus underwent some of these genetic shenanigans and then moved to the human population. Since the strain is new to us, immunity is low. It does appear that this new swine flu strain is being transmitted from humans to humans, which is not always a given—many strains are limited to one species, or can only move from a particular species to another.

So what we may have here is a perfect storm of sorts; a flu virus to which we have little immunity (this year’s flu shot won’t cover it), and an ability to pass it from person to person. Still, this doesn’t mean it will be some horrid medieval killer. Yes, the number from Mexico are discouraging, but so far at least, the impact in the States has been minimal. This is certain to change, but where it will go from here is unclear.

The flu isn’t magic. It’s a virus we see every winter. It passes through respiratory droplets, so if it hits hard, masks and frequent hand washing will go a long way. Drugs exist to treat these infections, and the U.S. has an additional emergency stockpile. Also, hospitals and local public health departments have emergency pandemic plans (which we will hopefully not need). Unfortunately, the only way to really know how well (or badly) we’ve prepared is to get hit with a pandemic.

We may have that chance.


  1. #1 Danimal
    April 27, 2009

    Luckily I made it through the winter with not even a cold. Today is suppose to be 90F in Maryland. With my father being a career ex-soldier, I remember in the 70s where all soldiers had to take a Swine Flu shot. Not anti-vax, but the shot did cause the death of a number of our soldiers, to the point that a number sued to government so they would not have to take it.

  2. #2 Michael Simpson
    April 27, 2009

    I’m wondering if we might be spared an epidemic because it’s approaching summer, and most of us aren’t closed up in offices, buildings, schools etc. I can’t remember if the reasons for most flu epidemics being in the winter was because of the close contact, or it happened for unknown reasons, and I’m recalling some urban myth.

  3. #3 PalMD
    April 27, 2009

    the reason behind seasonal influenza isn’t clear. see scienceblogs.com/effectmeasure and check out the flu cat

  4. #4 jj mollo
    April 27, 2009

    There has been a lot of back-and-forth on the issue of wearing masks. People have stated with certainty that it provides no benefit, and other people have stated with certainty that it’s very effective. What’s your opinion?

  5. #5 PalMD
    April 27, 2009

    Evidence isn’t great one way or the other but expert consensus is for masks, but N95 vs reg surgical masks isn’t well known either

  6. #6 srrab
    April 28, 2009

    After the federal gov’t made a mess of the Katrina response, I’m sure the new administration is working very intently to appropritately respond to this outbreak.

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