For much of human history, measles has been seen as a dangerous rite of passage in childhood. It’s more than just a bit uncomfortable, however. As many as 1 out of every 20 children with measles gets pneumonia and around 3 in 1,000 children don’t survive. But research shows that even for the majority of kids who make it out without major problems, measles leaves behind a problematic legacy.
Scientists are finding out that even in children who recover well, the virus doesn’t just infect their bodies—it erases part of their immune system’s memory, leaving them vulnerable to diseases they had already conquered.
Immune amnesia
The first major clue that measles had a deeper effect on the body came from epidemiologists tracking childhood deaths. In 2015, Michael Mina, then a researcher at Princeton University, noticed something odd: In the years before widespread vaccination, measles outbreaks were often followed by spikes in deaths from other infections. The trend stood strong in historical data from the U.S., U.K., and Denmark.
It wasn’t immediately clear at all why this was happening. Measles itself is deadly, claiming more than 100,000 lives per year worldwide, mostly children under five. But the death toll seemed to extend far beyond the acute infection. Mina and his colleagues proposed an idea: that measles was weakening immunity for other pathogens.
To test this, they analyzed blood samples from 77 unvaccinated children in the Netherlands, taken before and after a 2013 measles outbreak. Study co-author Rik de Swart had gathered blood samples from unvaccinated children during this outbreak. They found that measles had wiped out between 11% and 73% of the children’s antibodies—proteins that help the immune system recognize and fight off viruses and bacteria.
The implications were concerning. If a child had built up immunity to, say, chickenpox, measles could erase that protection, making them almost as susceptible as if they had never been exposed before. The virus didn’t just suppress the immune system temporarily—it hit a reset button.
This seemed almost too severe to believe.
To confirm this effect, scientists turned to a different model: monkeys. A separate study found that macaques infected with measles lost between 40% and 60% of their existing antibodies. The results suggested that measles destroys a crucial type of immune cell called long-lived plasma cells, which reside in bone marrow and churn out protective antibodies for decades.
In essence, measles was forcing the immune system to forget.
How measles rewires the body
This finding triggered a race to see what was happening.
A key piece of the puzzle had actually been discovered earlier. In 2002, a group of Japanese scientists discovered that the measles virus binds to immune cells. This is surprising because measles is a respiratory virus, so you’d expect it to bind to the lungs or somewhere in the respiratory system. So researchers used this information to piece together what was happening.
The virus gains entry by hijacking specialized immune cells called memory B and T cells, which store information about past infections. Once inside, measles spreads through the bloodstream to organs like the spleen and lymph nodes. As the immune system fights back, these infected memory cells are destroyed, along with their record of past battles.
This is where things get a bit murky. This destruction isn’t total. Survivors do gain lifelong immunity to measles itself. After that, the immune system also rebuilds—but not in the way it was before. New memory cells are created, but they’re now measles-focused and less on other, previous infections.
Some researchers call this the “measles paradox.” It’s not permanent, with this immune amnesia lasting 2-3 years. During this time, measles survivors face a higher risk of secondary infections. In the past, these secondary infections—pneumonia, diarrheal diseases, and other childhood killers—accounted for a big part of all measles-associated deaths.
A vaccine that fully protects against measles
There’s a clear connection between vaccination rates and cases of measles.
The good news is that existing vaccines also prevent this process. By blocking the virus from infecting the immune system in the first place, it also preserves immunity to other diseases. A single dose of vaccine is 93% effective at preventing measles, while two doses offer 97% protection.
Yet, unfortunately, we’re seeing an increase in anti-scientific claims that lead to lower vaccination rates, and the effects are already showing.
In early 2024, an outbreak in Ohio highlighted the dangers of low vaccination rates. The outbreak, which sickened dozens of children, was traced to a community with low MMR (measles, mumps, and rubella) vaccine uptake due to vaccine hesitancy. Nearly all infected individuals were unvaccinated. Something similar is happening in 2025 in Texas and Ontario, with the US reporting the first death attributable to measles in a decade.
We’ve already seen that if vaccinations drop, things can turn south quickly.
In 2019, a devastating measles epidemic in Samoa infected 5,667 people—8% of the population under 15. The outbreak was fueled by plummeting vaccination rates after misinformation spread about vaccine safety. Ironically, the antivaccination campaign in Samoa was supported by Robert F. Kennedy Jr., today’s health Secretary in the US. In a desperate effort to control the outbreak, the Samoan government declared a state of emergency and launched a door-to-door vaccination campaign, but not before 81 people—mostly children—lost their lives.
In light of recent findings, keeping measles at bay is more important than ever. Even if measles itself doesn’t seem severe, its aftershocks can be threatening. The virus erases a person’s immunological history, leaving them vulnerable in ways they never expected.
We have an extremely efficient weapon against this problem: vaccination. Whether or not we’ll end up us.
