Back in the 1960s, the United States began vaccinating children against measles. This had a number of health benefits, from an obvious reduction in measles cases and especially measles related deaths, to a decrease in birth defects caused by maternal rubella infections. But there was also a benefit that nobody could explain at the time: childhood deaths form all other infections diseases dropped, significantly.

Until recently, the presiding explanation for this was that children who received the measles vaccination were more likely to receive other vaccinations and better health care overall. That may have had something to do with it, but recent research shows there’s something else at work.


A magnified strain of measles. Image: Yale Rosen via Flickr CC.

Like many diseases, measles suppresses the immune system, in some cases for up to two or three years after the disease has run its course. What this means is that other diseases have an easier time infecting and, sometimes killing children who recently had the measles. By severely reducing the number of measles infections through the use of vaccinations, doctors were essentially protecting children from other diseases as well. Of course, getting the measles vaccine didn’t necessarily prevent other diseases (aside from the mumps and rubella, which were covered by the same MMR vaccine), but it did keep kids healthy enough to fight those diseases off in the first place.

What’s even more interesting is that, beyond acting as an immunosuppressant, measles also creates a kind of immune system amnesia. Normally, with a virus, once the immune system defeats that virus, it won’t infect the body again (hence the name immune system). But measles causes the immune system to forget how to fight some other diseases, meaning that, after measles, you might develop the chicken pox again. And since the immune system is already weak, that disease is more likely to infect and more likely to last longer.

This is especially important news considering recent “anti-vax” movements in America and the United Kingdom, as diseases like measles have started to make a comeback, and threaten the lives of millions of children.