Just one dose of the measles-mumps-rubella (MMR) vaccine provides 95% protection against the disease, and second dose brings that number up to 98-99%. But it turns out that the vaccine doesn’t just combat measles—it defends against other infectious diseases, as well, and for far longer than researchers originally suspected.
That’s because measles drains the immune system of its otherwise powerful memory: Measles ravages victims’ bodies to such an extent that the immune system forgets how to destroy other pathogens it had fought in the past. So by receiving a measles vaccine, you’re actually warding off future (preventable) infections, too.
Most scientists already knew about measles’ effect on the immune system—but they believed this immunosuppression lasted no more than a few months after measles is flushed from the body. However, more recent studies of children in developing countries, who are typically exposed to more diseases, have suggested that the effect lasts for up to five years. How could this be? Here’s Mitch Leslie, writing for Science:
In the days before vaccination, measles was responsible for about half of childhood deaths from other illnesses, the team says. With that many dead children, why didn’t researchers detect this connection before? Many assumed that measles’ impact on the immune system quickly faded, Mina says. “So when a kid gets pneumonia 6 months later, nobody would link that to measles.”
Now, a new study in the journal Science claims that measles survivors in developed countries remain vulnerable to other infections for at least two years (compared to developing countries’ five) after recovering from the disease. A team of researchers analyzed measles data from the United States, Denmark, and part of the United Kingdom to find out whether deaths from other infections correlated with the number of measles cases in a given year or years. They concluded that children in high-income countries who survive measles remain vulnerable to other diseases for an average of 2.5 years. Even more impressive, that average number was nearly the same for all three countries studied.
The team’s mathematical analysis suggests that measles’ effect on the immune system lasts much longer than previously thought. A vaccine, then, could halt that vulnerability and fortify measles sufferers against other maladies, as well.
Still, some experts express doubts about the study’s validity. They argue that the results are, at best, merely indirect evidence that measles suppresses the immune system for long periods of time. For them, the best proof would be if scientists can find specific individuals who first survived measles and then died of a different infectious disease.
Still, a vaccine guarding against measles may benefit its recipient in more ways than one—especially if enough people agree to get it.