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A Really Important Fact About Vaccines (That Not Everyone Understands)

14329622976_2ae10f5741.jpgI was reading about the recent cases of measles in a bunch of people who were at Disneyland in December--and it made me sad. This doesn't have to happen. A simple vaccine can prevent measles.

And we want to prevent measles, because it can be dangerous.

We are seeing more outbreaks of measles--in part because some families are choosing not to vaccinate their children. They are afraid of side effects of the vaccine. But here's a really important fact that everyone needs to understand: vaccine-preventable diseases are always more dangerous than the vaccines that prevent them.

Think about it: if this weren't true, there would be no point to the vaccine in the first place. Primum non nocere, first do no harm, is a really important concept to us doctors.

Let's use measles as an example, since we are seeing outbreaks of it. According to the Centers for Disease Control and Prevention, 1 in 10 of those who get measles will get an ear infection or diarrhea. That's not such a big deal--but there are other complications that are a big deal:
-1 in 20 will get pneumonia.
-1 in 1000 will get encephalitis, an inflammation of the brain, which can lead to seizures, deafness, or mental retardation.
-1 or 2 in 1000 will die.

Now, let's compare this to the risks of side effects from the vaccine. 1 in 6 will get a fever, 1 in 14 will get some temporary pain or stiffness in their joints, 1 in 20 will get a rash, 1 in 75 will get swollen glands. None of these are that bad, and all go away. Here are the risks of more serious side effects:
- 1 in 3000 will get a seizure from a fever (for the MMRV vaccine, a combination vaccine that also protects against chicken pox, that number is 1 in 1,250)
- 1 in 30,000 will have a drop in their platelet count, which could possibly (but not necessarily) lead to bleeding
- While there have been events such as deafness, long-term seizures or brain damage reported after the MMR, they are so rare that we can't be sure that the vaccine actually caused them.

The risks of all of these serious side effects are smaller than the risk of dying of measles.

When vaccine-preventable diseases like measles are very rare, it changes the math a bit--because the chance that you could end up catching it becomes small. But these days, you can't count on them being rare. It used to be that enough people were immunized that it ended up protecting those who weren't (we call this "herd immunity."). But as more and more people refuse vaccines, and as more and more people travel to and from countries where vaccine-preventable diseases are more common, all of that is changing.

Please, parents, think long and hard before you refuse a vaccine. Get the facts. Do the math. Talk to your doctor if you have any questions.

Vaccines save lives. It's that simple.

Photo credit: 2014 NIAID, Flickr | CC-BY | via Wylio

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