Flu Vaccine or not?

I've been getting a vaccine shot for the past few years, and I wanted to revisit the topic to see if it was a good idea to keep doing it or not.  What I learned is that good information is really hard to come by.  I also learned that getting vaccinated is very unlikely to help you, but may help society as a whole.

To get to the heart of the matter, I tried to answer these questions:

• How likely am I to get the flu in any given year?
• How likely is it to kill me if I do get it?
• How much less likely am I to get the flu if I get vaccinated?
• How likely am I to suffer serious side effects from the vaccine?

If you don't want to read the rest, the cliff-notes answers are: 1) Around 1 in 400 2) Very unlikely 3) About 50% 4) No friggin' clue, but there is some chance.

I say "I" above, but I really mean "me, my wife, or my kids".  

Definitive answers on this are pretty hard to find.  For instance, the CDC's page on effectiveness of the vaccine really set off my bullshit detector.  It describes the details of how statistics are compiled, confidence intervals, etc, etc, and then gives you one number with no citations for it.  Worse, it's a relative-risk number, which I consider to be questionable without seeing the absolute risk numbers along side.  

Why absolute risk?  Well if the risk of contracting a given disease is vanishingly small, a vaccination doesn't make sense at all because there is always some risk of side-effects.  For instance, someone may develop a vaccine reduces your risk of fatal Floogle's Syndrome (I made that disease up) by 80%.  If the overall incidence of Floogle's Syndrome is 1 person in every 100, it's worth risking quite a few side effects to avoid it.  If the incidence is 1/200,000,000 (that is, 30 people in the entire world), it isn't worth taking any precautions - your chance of getting it is too small to bother with.

Some statistics

Using the CDC's numbers for last year's flu season, it's 1.5% across the entire flu season.  But, that's for "ILI", or "influenza-like-illnesses".  I found this study which showed that only 17% of children who saw their doctor for "the flu" actually had a variant of the influenza virus.  If that applies across the whole population, it means that your chance last year, here in Michigan, was 0.17 * 0.015 = .25%.  This same study showed that if the children were vaccinated, the vaccine was effective in 58% of cases.

If I did the math right (check it yourself - I might not have, and I made a few assumptions above), that means getting your kids (or yourself) vaccinated is likely to help avoid the flu 0.15% of the time in a given year. To put it into perspective, if you live over 600 years and get vaccinated every year, you can avoid one case of the flu.  If you live to be 100, there is a 1 in 6 chance that getting vaccinated every year for your whole like will help at all.

If you think my numbers are optimistic, double them.  That's still a 1 in 3 chance that the vaccine will help you over a lifetime. 

But what if the flu is likely to kill you?  

I'd consider a 1 in 6 chance of avoiding premature death worth it.  We know that influenza isn't certain death, though.  I can't tell how uncertain it is because every site I looked at (like this one from the CDC again) lumped influenza and pneumonia together.  That said, the same sites tell us that pneumonia accounts for 98% of the deaths in that number.  

Pretty much all of the sites I looked said that "flu and pneumonia are the 8th leading cause of death", and used that as an argument for flu vaccination.  Since flu itself accounts for around 2% of that, flu is more like the 50th leading cause of death, not the 8th.  That's way below most cancers you could name, and about on par with epilepsy.  Thats a serious condition, but how much time do you spend worrying about it if you haven't been diagnosed with it?

But what about side-effects from the vaccine?

This is where things get really murky.  I can't quote a single study that gives solid numbers, though there is a lot of anecdotal support.  In other words, side-effects - including some serious ones, do happen.  I just don't have any reliable way to tell how frequently they occur compared to the beneficial effects of the vaccine.

Fear-mongering

The CDC and other health organizations seem to always use fear as a way to motivate people to get vaccinated. They talk about risks, then use statistics to obscure what the actual risks are.

That doesn't mean they're assholes.  I think that they're sincere, professional people who really want to help.  I also think that many people who work in epidemiology want to justify their grant money to continue their research and build an infrastructure so when they develop a truly effective vaccine, it will make a difference.  

I don't agree with the way they do it, though.  It smacks of an elitist view that most people are too dumb to make the right choice if you give them all of the information.  There might be some truth in that (though I'd say "don't take the time to think it through" rather than "too dumb"), but so what?  Lying with statistics is still lying.

Conclusion

So, the flu is unlikely to kill you, you have maybe a 1 in 400 chance of being exposed to it in any given year, and the vaccine will prevent it only about half of the time if you are.  Side effects happen, but they seem to be unlikely.  Is it worth it to get vaccinated?

Probably not.  

Most of the relatively small number of deaths occur in the 65-and-over age group.  That may make it a bit more sensible for you if you're over 65 or you live with someone who is.  If you live in a warmer climate, the chances are slightly higher.  Overall I don't buy it, though.  As a means of improving reducing your risk of illness, you're better off taking a couple of long walks than spending your time getting vaccinated.

Getting vaccinated against the flu is an altruistic act.  By getting a vaccine, you help reduce the total number of cases that a doctor has to handle.  You reduce the chance of giving someone else the flu.  If another pandemic like the 1918 outbreak occurs, you're supporting the infrastructure to quickly distribute a vaccine that actually will save a lot of lives, including yours.

Maybe.

I think I'll pass on getting the vaccine this year, though.