Down with the Sickness

H1N1 fever is sweeping the nation, kids, and so it's time for ONAF to look at this supposedly SUPER-DEADLY DANGEROUS OUTBREAK OMG!!!11!1!!1 and see if the panic is warranted.

First, there's not a lot of data we can go on right now. Flu season hasn't begun in earnest yet, so current infection and hospitalization rates aren't really indicative of what the final rates would be. We can, however, get a sense of how dangerous the virus is compared to the normal flu by comparing the mortality rate of H1N1 with the mortality rate of the average flu.

The CDC, ever helpful, provides both in this web page, but of course you have to go digging for it. The normal flu, claims the CDC, kills 36,000 and hospitalizes more than 200,000. We'll assume that those who die of the flu are hospitalized first - that leads to a mortality probability of roughly 0.18 for flu infections serious enough to require hospitalization. (That number seems a bit high to me, but it's corroborated by the academic literature.)

So what has the swine flu wrought? So far, there have been 4958 confirmed H1N1 hospitalizations in the U.S. and 292 deaths. That's a mortality probability of 0.059 - far less than the standard seasonal flu. Not all infections lead to hospitalization, of course, but it's reasonable to expect that similar symptoms would lead to hospitalization for both seasonal and H1N1 flu.

Now I'm not prepared to say that this means the H1N1 virus is less deadly than the seasonal flu, but that appears to be the case right now. So why the disparity? The reason could be that H1N1 tends to infect younger people. For some reason, old people - those most at risk for death from the seasonal flu - aren't getting H1N1 at anywhere near the normal rate, while younger people are getting H1N1 at a higher rate than normal. Since H1N1 is infecting lower-risk populations, one would expect the mortality rate to be significantly lower.

So why the hysteria over H1N1, if it's not any more dangerous than the seasonal flu? One reason is that it's a novel flu strain that people haven't experienced before. This means more people will get H1N1 than would normally get the seasonal flu, as natural immunities to the seasonal flu strains won't protect people against H1N1. The hysteria is certainly misplaced, but it's worth noting that because of H1N1, this flu season will probably be a bit worse than normal flu seasons. It's not a super-deadly strain of influenza, though, and fears of a 1918-style pandemic are overblown. Flu symptoms from H1N1 might be worse because of the lack of antibodies in the average person's system, but so far it won't kill you any more than season flu would.

The final question revolves around the vaccine, and I'd like to pose a question to the commentariat here. Novartis' documentation says their H1N1 vaccine is only intended for children ages 4 and up. Is there a toddler version of the vaccine that is proven safe for little people like my daughter? Has anyone heard differently about kids under 4 not being recommended for the vaccine? Anyone know who the FDA approved it for?