Is there any good reason not to mandate national vaccination?

[WhyNot]

[QUOTE=some antivaxxer WhyNot quotes]
If the vaccines work, why would the vaccinated kids & teachers be in danger from those who haven’t been vaccinated??
[/QUOTE]

@panache45

This is pretty much my position, as well as Darwin’s.

I actually respect this position. I respect it because it’s a perfectly logical position when you don’t know how vaccination works. It’s logically consistent if one assumes that vaccination is 100% effective and if one assumes that those who are vaccinated cannot transmit the disease to others. So I like this because it’s the reasoning of a logical person with good critical thinking skills who is misinformed.

Unfortunately, neither of these assumptions are true. We do a terrible job of teaching how vaccination works, so that’s not your fault. But there were two posts on a thread here on the SDMB that I think address this issue and a related issue very well. Once you’ve read them, your position should change. So, buckle your seatbelt and pour another cup of coffee, we’re about to shift your brain!

@WhyNot

@Uber_the_Goober

Understood, accepted, got it.

So it’s really a question of whether or not I *care *that evolution will actually be working the way that it should…

Those born with immunity, or able to immunize themselves, don’t die. The rest, do.

No, you still don’t got it.

You get a vaccination. Yay! It will reduce the chances that you’ll get the disease. Reduce. Not eliminate. Reduce.

So then I get vaccinated. Yay! It will reduce the chances that I’ll get the disease or that I’ll pass it to you. Reduce, not eliminate.

So now **curlcoat **doesn’t get vaccinated. She goes to Germany and gets measles, but before she gets symptoms, we pass her in the produce section and she coughs on us.

Ooops! We’ve only reduced, not eliminated, our risk of catching it from her. Like most people that have been vaccinated, I don’t get it, nor do I pass it on to you.

You aren’t so lucky. Your vaccine reduced, but didn’t eliminate your chances of catching it. You got it, and you’re dead. Or meningitis or pneumonia or hepatitis (all potential complications of measles, more common in adults than children) or if you’re really lucky, you just miss two weeks of work and income feeling like crap.

That’s herd immunity in a nutshell. Vaccines are effective, but not quite 100% effective. Add up a bunch of not-quite-100% effectives, and some of us who were vaccinated *will *get sick, just like some number of people will get pregnant each year despite using 98% effective birth control pills.

And this one, which finally helped me understand something that has always bothered me: most people in many vaccine preventable disease outbreaks are vaccinated…but that is *not *an indication of vaccine ineffectiveness. (Blew my mind, this one did. Spoiler alert: math did it.)

@Andy_L

Yeah. When you get vaccinated, you directly reduce your chance of catching a disease if you’re exposed to it. When other people get vaccinated, it indirectly reduces your chance of getting a disease because it reduces the chance that you get exposed. Obviously, reducing your chance of getting exposed and reducing the chance of catching the disease if exposed, is really good news.

While we’re dealing with common vaccine misconceptions, here’s an interesting one. Suppose there’s a vaccine that is 90% effective in preventing disease, and 50% of the population gets the vaccine. In a population of 1000 people in which everyone is exposed, 500 people get the vaccine, and of those only 50 people get the disease, while all 500 of the unvaccinated people get the disease. So in the 1000 person population, only 550 get the disease.

Now raise the percentage of people who get the vaccine to 90%. 900 people get the vaccine, and out of them 90 people get the disease, while all 100 unvaccinated people get the disease. Only 190 people get the disease, but notice that almost half of them are vaccinated. This doesn’t mean that the vaccine isn’t working - it means that most people are vaccinated.

It can get even more confusing - when vaccine uptake gets to 95%, 950 people get vaccinated, and of them, 95 people get the disease; meanwhile only 50 unvaccinated people get the disease. Now the majority of 145 people who got the disease were vaccinated - but again this is because the vast majority of everybody was vaccinated. A clearer way to express this is that even though the unvaccinated make up only 5% of the population, they made up over 30% of the people who caught the disease.

I hope these two posts help you to understand why “you protect yours, and it doesn’t matter what I do with mine” doesn’t work in the real world, where vaccines aren’t 100% effective, and even the vaccinated can get and spread the disease - just not as frequently as the unvaccinated.

Keeping vaccine preventable illness at bay relies on a certain percentage of people being vaccinated so that enough of us are immune that the viruses don’t have a lot of places to live. The percent varies by disease, but 94% is about right. We can have 6% of our population to go unvaccinated without greatly raising the risk of an epidemic. Most of those “slots” are already taken up by legitimate medical reasons not to vaccinate - like egg allergies, impaired immune systems, family history of severe reaction to a vaccination - or by those who get vaccinated but their body doesn’t form immunity. There are very few “slots” left for religious/philosophical/just can’t be bothered objectors. Every person who decides to exempt themselves from the pool of vaccinated folks moves us closer to the line where not enough of us are vaccinated to keep the viruses at bay.