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Measles has a stealth side effect: New research shows it erases much of the immune system's memory of how to fight other germs, so children recover only to be left more vulnerable to bugs like flu or strep. Scientists dubbed the startling findings "immune amnesia." The body can rebuild those defenses — but it could take years. And with measles on the rise, "it should be a scary phenomenon," said Dr. Michael Mina of Harvard's school of public health, lead author of research published Thursday in the journal Science. (Neergaard, 10/31)

The weakened immunity leaves a child vulnerable for several years to other dangerous infections like flu and pneumonia. The damage occurs because the virus kills cells that make antibodies, which are crucial to fighting off infections. Scientists call the effect “immune amnesia.” During childhood, as colds, flu, stomach bugs and other illnesses come and go, the immune system forms something akin to a memory that it uses to attack those germs if they try to invade again. The measles virus erases that memory, leaving the patient prone to catching the diseases all over again. (Grady, 10/31)

The discoveries have enormous and immediate public health implications, researchers and clinicians said, and underscore more than ever the importance of measles vaccination. In recent years, anti-vaccine misinformation has been one reason vaccination rates have plummeted and global measles cases have surged. This year, the United States has had 1,250 cases of measles, the most since 1992. (Sun, 10/31)

Dr. Michael Mina, first author of the Harvard paper, said the phenomenon bears some similarities to the one that takes place after HIV infection. HIV also infects immune system cells. “If you took the first 10 years of somebody having HIV and you squished that into a few weeks, that’s the kind of memory damage and immune damage you get from measles,” Mina, an assistant professor of epidemiology at Harvard’s T.H. Chan School of Public Health, told STAT. (Branswell, 10/31)

“The measles virus is like a car accident for your immune system,” said Harvard University geneticist Stephen Elledge,the senior author of the Science study. An unvaccinated child who weathers the measles may emerge only slightly the worse from such a crash. Or he might sustain an injury from which it takes months or years to recover. (Healy, 10/31)

Previous evidence for immune amnesia has been based on mathematical models and population-level studies according to Dr. Michael Mina, assistant professor of epidemiology at the Harvard T.H. Chan School of Public Health and the primary author of the study released this week in Science. The new studies are the first to show "any of the real biology that helps explain the population-level effects," he says. (Vaughn, 10/31)

This year has seen measles outbreaks all over the world, even in places that had previously eliminated the virus. Just a few months ago, the United States experienced its largest outbreak since 2000, which was so severe experts feared the country would lose its measles elimination status. In August, four European countries lost their measles-free status when the disease made a comeback after being eradicated years ago. (Yeung, 11/1)

In a related study published Thursday in the journal Science Immunology, researchers using the same study population of children from the Netherlands as in the Science study reported on how the measles virus affects immune cells called B cells. "This study is a direct demonstration in humans of immunological amnesia, where the immune system forgets how to respond to infections encountered before,” study author Velislava Petrova, a researcher at the Wellcome Sanger Institute in the United Kingdom, said in a statement. “We show that measles directly causes the loss of protection to other infectious diseases." (Stenson, 10/31)