Surviving measles doesn’t mean you’re in the clear.
In 2025, the US saw a dramatic spike in cases, with the CDC reporting the highest levels of the highly contagious disease in over 30 years.
Now, health experts are sounding the alarm about a little-known complication that can make your body forget how to fight off future infections — putting you at risk for years after your initial symptoms fade.
Known as immune amnesia, it occurs when the measles virus attacks the cells in your immune system responsible for remembering past infections.
Normally, these “memory” cells help your body recognize and fight off pathogens it’s already encountered. But when measles wipes them out, your immune system forgets how to defend against viruses and bacteria it has already defeated.
“You [usually] have a couple of hidden cells in there that remember this and go, ‘Wait, I know this virus. Make antibody X,’” Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital, told The Post. “Immune amnesia turns that idea off.”
This immune reset can leave you defenseless against threats your body once knew how to fight. In fact, a study found that a measles infection can wipe out up to 73% of a child’s existing antibodies.
“If you have measles, your cells that would have made antibodies [for other diseases] forget how to do it, and you’re kind of immune immature,” Nachman said.
“And the things that you had other vaccines for or made antibodies of the past, your body forgot how to do, and you’re kind of at risk all over again,” she explained.
It also makes you particularly vulnerable to developing severe secondary infections, like pneumonia and chickenpox.
And the danger doesn’t end once your measles symptoms subside. Research shows that even after recovery, your immune system can stay suppressed for several months — and in some cases, for up to five years.
“The threat measles poses to people is much greater than we previously imagined,” Stephen Elledge, senior author of the child antibody study, said in a statement.
“We now understand the mechanism is a prolonged danger due to erasure of the immune memory, demonstrating that the measles vaccine is of even greater benefit than we knew.”
The CDC reports that after two doses, the measles, mumps and rubella (MMR) vaccine is 97% effective at preventing measles.
Recent studies also show that the shot may boost the function of certain immune cells, making them more effective at fighting off other diseases as well.
Yet despite these benefits, vaccination rates have slipped in recent years.
For the 2024-2025 school year, only 92.5% of incoming kindergarteners had received the MMR vaccine. That’s below the 95% threshold public health experts say is necessary to prevent outbreaks.
The effects of this decline are already being felt. In 2025, the US reported 2,065 confirmed measles cases, with Texas, Arizona and South Carolina leading the pack, per the CDC.
Two hundred thirty-five of those cases resulted in hospitalizations, with more than half of the patients being under 19. At least three people died.
That’s a dramatic increase from 2024, when only 285 confirmed cases were reported nationwide.
In fact, the last time the US recorded more than 2,000 cases in a single year was in 1992.
“The US is at risk of losing its measles elimination status should cases continue at this rate,” William Moss, executive director of the International Vaccine Access Center, who co-leads the group’s measles tracking project, said in a statement.
“As vaccine confidence continues to be undermined, immunization is more important than ever to end this outbreak and prevent future outbreaks from occurring,” he continued.
The CDC recommends that children receive their first dose of the MMR vaccine between 1 and 15 months, with a second dose between 4 and 6 years old.
Unvaccinated teens and adults can still get vaccinated with two doses, spaced at least one month apart.
