Measles Can Damage the Immune System for Years

As more measles cases emerge around the country, doctors say they’re concerned that those infected may be at risk of long-term health complications.

A bout of measles sends the immune system into shock, demolishing critical cells that help our bodies respond to threats. This can leave people extremely susceptible to other pathogens for weeks after an infection.

The virus also attacks the immune system’s memory cells. These cells remember and recognize the pathogens you’ve encountered over the course of your life and protect against them, said Dr. Michael Mina, a former professor of epidemiology at Harvard T.H. Chan School of Public Health who has studied measles and immunity. Scientists call the phenomenon “immune amnesia.”

Everyone who gets sick from measles will experience some level of immune amnesia, Dr. Mina said. This happens on a spectrum. For some people, it might mean that coming down with the flu will keep them in bed for an extra day or two, he said. But others may lose far more immunity and wind up getting seriously sick from the viruses they encounter. This immune amnesia can last for around three years.

“A real concern is you’re not just going to get measles and get sick, but within the next couple of years, your kid’s going to be really vulnerable to a lot of other stuff,” said Dr. Aaron Milstone, a pediatric infectious disease specialist at the Johns Hopkins Children’s Center.

Measles can also cause severe, long-term complications. About one in 1,000 children who develop measles will experience brain swelling, which can cause hearing and vision loss, intellectual disabilities and permanent brain damage. And people of any age who are immunocompromised are at greater risk for developing a specific type of brain swelling that can occur for up to a year after they recover, said Dr. Milstone.

In extremely rare cases, adults and children develop subacute sclerosing panencephalitis, a fatal disease of the central nervous system. That disease, which can cause seizures, typically appears seven to 10 years after a patient has recovered from measles. There is no cure. By some estimates, around four to eleven per 100,000 cases of measles lead to the condition. The risk is slightly higher among children who are infected under the age of 5.

Around one out of every 20 children with measles develops pneumonia. The lung infection is the most common cause of death in children with measles. Even in children who survive, a severe case of pneumonia can impair lung function in the long term, said Saad Omer, a professor of public health at the University of Texas Southwestern Medical Center. The illness can scar the lungs, making it difficult to breathe properly. Children who develop pneumonia may also be more likely to develop asthma and chronic obstructive pulmonary disease as adults.

Most measles cases in the United States this year have been among children. But adults are also susceptible to long-term effects and severe infections.

In addition to people who are immunocompromised, adults over the age of 20 and children under 5 years old are at high risk for complications from measles, according to the Centers for Disease Control and Prevention. Measles is also dangerous for pregnant women, who are more likely to become hospitalized and develop pneumonia. Pregnant women are also at heightened risk for miscarriage, preterm birth and stillbirth.

Vaccines provide a lifelong defense against the virus for the vast majority of people, shielding them from both the short and long-term risks, said Dr. Walter Orenstein, a professor emeritus at Emory University and the former director of the National Immunization Program at the C.D.C.

“It’s about community protection, and not just individual protection,” he said.