Back in the 1960s, the U.S. started vaccinating kids for measles. As expected, children stopped getting measles.
But something else happened.
Childhood deaths from all infectious diseases plummeted. Even deaths from diseases like pneumonia and diarrhea were cut by half.
Scientists saw the same phenomenon when the vaccine came to England and parts of Europe. And they see it today when developing countries introduce the vaccine.
“In some developing countries, where infectious diseases are very high, the reduction in mortality has been up to 80 percent,” says Michael Mina, a postdoc in biology at Princeton University and a medical student at Emory University.
“So it’s really been a mystery — why do children stop dying at such high rates from all these different infections following introduction of the measles vaccine,” he says.
Mina and his colleagues think they now might have an explanation. And they published their evidence Thursday in the journal Science.
Now there’s an obvious answer to the mystery: Children who get the measles vaccine are probably more likely to get better health care in general — maybe more antibiotics and other vaccines. And it’s true, health care in the U.S. has improved since the 1960s.
But Mina and his colleagues have found there’s more going on than that simple answer.
The team obtained epidemiological data from the U.S., Denmark, Wales and England dating back to the 1940s. Using computer models, they found that the number of measles cases in these countries predicted the number of deaths from other infections two to three years later.
“We found measles predisposes children to all other infectious diseases for up to a few years,” Mina says.
And the virus seems to do it in a sneaky way.
Like many viruses, measles is known to suppress the immune system for a few weeks after an infection. But previous studies in monkeys have suggested that measles takes this suppression to a whole new level: It erases immune protection to other diseases, Mina says. Continue reading