With the anti-vax movement picking up more steam than it ever deserved to have, kids are being put at risk from serious preventable illness. Unfortunately, the anti-vaxxers aren’t just putting their own kids at risk, they’re increasing the risk for other kids as well.
Herd immunity refers to the extra protection that comes from vaccinating a threshold percentage of the population. Let’s say your herd consists of sheep in a pasture. If you vaccinate enough sheep, then it’s hard for an infectious agent to jump around in your pasture because there are so few bodies it can jump to. The vaccinated part of the herd then ends up protecting the sickly little lambs and the sheep who weren’t able to get vaccinated. Enough of the herd is protected that the infectious agent just can’t get to the vulnerable ones.
Getting back to humans, some people can’t get certain vaccines for medical reasons. That might be due to allergy, but often it’s because people who are immunocompromised (either due to a medical conditional or immunosuppressant drugs) can’t get what are known as “live vaccines”. These tend to be the same people that are most vulnerable to getting really sick if they’re exposed to an infectious agent.
This is a huge issue when it comes to the MMR (measles mumps rubella) vaccine. It’s a live vaccine, so immunocompromised people generally can’t get it. Measles is highly contagious, and that fast and easy spread of infection means that the threshold to achieve herd immunity is also high, at 93-95% (as per the WHO).
That doesn’t leave much room for anti-vaxxers to get in the way before the whole thing starts falling apart.
The World Health Organization reports that in 2017 there were 110,000 measles deaths globally, with most of the deaths in children under 5 years old. That’s a lot of entirely preventable deaths.
Ideally, almost everyone would be getting vaccinated, and measles, mumps, and rubella would all go the way of the dodo bird, just as smallpox was declared eradicated in 1979.
It’s disturbing that kids’ lives are getting put at risk because of concerns that vaccines cause autism, which study after study has shown not to be the case. It’s one thing when people want to choose nonsense, but when it puts kids’ lives (both their own and others) at risk that’s not ok.
There’s more on debunking pseudoscience on the science corner page.