The Daily Beast is joining the anti-vaccination conspiracy mongering so beloved of the Huffington Post. With the usual dark threatening noises about the possibility of brain injuries to children, and references to mercury based vaccine preservatives, there’s this bit of astounding mathematical illiteracy:
the venerable flu shot is only 62 percent effective in reducing symptoms of the disease. In other words, for every 100 people who get the flu shot, 38 of them will get the flu anyway.
There are two ways of reading this number. One is: OH MY GOD! 38% OF PEOPLE WILL GET THE FLU! THAT HAS TO BE AN EPIDEMIC!* And, seeing as, on average, only 5-20% of the population gets the flu anyway, this means that the vaccination causes from almost double to seven times more people to get the flu than no vaccination at all! OH NO! THE FLU VACCINATION IS CREATING A FLU EPIDEMIC! WITH MERCURY!
The second way to read this immediately struck me: That author doesn’t know what that percentage means. It’s not 38% percent of the total vaccinated population will get the flu, it’s got to be that only 38% of whatever number would have got the flu anyway will get it if vaccinated. In other words, there’s a 38% reduction in the number of people who get the flu.
Not a giant increase.
The article cites the CDC for the 38% number. And here’s what the CDC says:
Findings from early data suggest that this season’s vaccine so far is reducing the risk of having to go to the doctor for influenza by about 60% for vaccinated people.
Yep. That would be a reduction in the number of people who have the flu. How many people are having the flu this year? The CDC says 5-20% of folks get the flu every year. So what this means is that, if, say, we would have had an epidemic of flu and 10% of the general population got it, only about 3.8% of the vaccinated population would get it. And that, of course, doesn’t account for the reduction of exposure from all those vaccinated folks who successfully avoided the flu.
It took only about 3 minutes to pull these numbers from the CDC site with a little Google aid.
The CDC is also good with the mercury nonsense. They note that the single-dose vaccination, which I got, does not contain themerisol (once the source of mercury in vacines, although not much any more) , and that the overwhelming scientific evidence demonstrates that thermerisol is safe.
*The epidemic threshold for the flu is seven percent.
Here’s a coupla other other viewing angles:
Of every 100 people who do not get the flu shot, 100 have no protection against flu.
Of every 100 people who get the flu shot, 62 will not contract flu.
I was a PE major … but even I can understand those kinds of odds.
Daily Beast is going to a subscription service. I’ll keep my money and buy another Harley T-shirt.
Also, IIRC, those vaccinated are likely to have a much easier time of it if they *do* get the flu.
I got the flu in NYC while in grad school. Twice. Spent nearly a week in bed each time. It’s great for making it all the way through Infinite Jest, but other than that, not much to recommend it. I get my flu shot every year now.
(OTOH, my doc says I have high cholesterol & need to take statins, but I’m pretty skeptical; I should cut out red meat & start exercising, but I doubt statins will make much difference either way.)
It’s always valuable to call individuals and publications on this kind of gross misunderstanding.
Of course, these numbers also tell us that our chances of not getting the flu are at least 80-95 percent, even without the vaccine, and with lots of people getting the vaccine even better. So maybe we should worry about something else.
I got the flu last February. That was only the second time I’ve had it but it was horrifying enough that I will ALWAYS get a flu shot from now on. That was ten days of pure hell. My boyfriend brought it home and if I’d had the energy, I would have killed him for it.
I will attempt a few corrections. I hope I get them right.
“In other words, there’s a 38% reduction in the number of people who get the flu.”
The relative reduction is 62%, equal to 100% minus the 38% who do not receive production from the vaccine.
“Of every 100 people who get the flu shot, 62 will not contract flu.”
The odds are even better. Assuming an unusually high infection rate of 20% among the unvaccinated and a low vaccine effectiveness of 60%, the chance of influenza infection for a vaccinated person is 0.2 * (1 – 0.6) = 0.08 or 8%. The absolute reduction, then, is 12%. Assuming a low infection rate of 5% among the unvaccinated and the same effectiveness, the chance is 0.05 * (1 – 0.6) = 0.02 or 2% with an absolute reduction of 3%. Even better, the quoted 62% effectiveness applies to groups, including as the elderly, who do not develop immunity as readily after vaccination. The vaccine is significantly more effective than 60% in non-elderly adults and older children.
The greater problem at work here and too many places elsewhere is the fraudulent point/counterpoint approach to journalism. The Daily Beast also carries this one arguing in favor of vaccination. Putting forth both sides of an argument is bad journalism, in my non-journalist estimation, when one of the sides is plumb wrong on so many accounts. Perhaps it can be helpful in the case that the plumb wrong side is revealed to be balderdash in the process, but too often media spread garbage that is hard to see for what it is under the false banner of fairness.
“receive production” -> “receive protection”
It is scary to watch lawyers attempt to do math.
Y’all cut it out.