Warning: A lot of number crunching, estimation and wild guessing follows...
I was listening to this item on NPR recently and the numbers quoted didn't really make much sense to me. They're saying 6 out of the 45 deaths recorded in a 2 month period were pregnant women, and that this means that they should definitely get vaccinated because of the increased risk.
But what does that mean in real numbers? A sample size of 45 is awfully small to make predictions for the general population. Is it reasonable to scale that up to the 300,000,000 people in the US? Assuming it is, what sort of numbers does that really translate into? I mean, you can talk ratios and percentages but, when it comes down to it, how many people are actually at risk?
The latest figures I'm seeing are that 1,000,000 people in the US have been infected and 600 of them have died. This works out to a fatality rate of 0.006 (0.6%). And from the NPR article, it sounds like 6/45ths (13%) of the deaths are pregnant women. This is quite high given that pregnant women make up only about 1% of the population.
I'm seeing a lot of fuzzy figures about how many are likely to become infected this season but it seems to range from 25% to 50% of the population. Let's go with the more conservative 25% and see what happens if no one gets a shot...
Nobody Gets Vaccinated
Population of the US = 300,000,000
Infected = 300,000,000 * 25% = 75,000,000
Deaths = 75,000,000 * 0.6% = 450,000
Pregnant woman deaths = 450,000 * 13% = 58,500
Now, the major reason I've heard for not getting a flu vaccine is that you could get Guillain-Barré syndrome which can be fatal. In 1976, 50,000,000 received the swine flu vaccine. Of those, 25 died of Guillain-Barré syndrome. That's a fatality rate of 0.00005%. Let's say everyone gets a swine flu shot this year...
Everybody Gets Vaccinated
Population of the US = 300,000,000
Vaccinated = 300,000,000 * 100% = 300,000,000
Deaths from Guillain-Barré syndrome = 300,000,000 * 0.00005% = 150
Pregnant woman deaths = 150 * 1% = 2
In actuality, the CDC is recommending shots for only half the population (150,000,000), so the Guillain-Barré deaths would be 75 people. The number of pregnant women who would die would remain the same, since the CDC is recommending all of them get a shot. In addition, some of the people who didn't get a shot would die from the swine flu. Hard to estimate how many but, since they're apparently a lower risk group, that figure would be considerably less than half of the 450,000. Call it 100,000.
Quick recap:
No vaccine = 450,000 deaths (58,500 pregnant women)
100% coverage = 150 deaths (2 pregnant women)
50% coverage = 100,000 deaths (2 pregnant women)
OK, so, there's a lot of figures pulled out of (nearly) thin air and I might've screwed up the math in there somewhere. There are a lot of unknown factors too. How many people will be infected before the vaccine is available? How effective is the vaccine? Does the 1976 Guillain-Barré rate apply to the current vaccine? Do the current fatality rates scale up for the general population?
Thing is, even if I'm way off on these numbers, it still looks like the risk of getting the vaccine is far outweighed by the risk of not getting it.
Personally, I think I'll get the shot, if it's offered to me. That's assuming I don't catch the swine flu first. As luck would have it, I've got a sore throat today (cough cough).