Measles Can Cause ‘Immune Amnesia,’ Wiping Out Defenses Against Other Infections

With a measles outbreak continuing to spread in the United States, concerns have grown about the possible devastating outcomes of the virus, including pneumonia, encephalitis (brain swelling), and even death.

Measles can also lead to other long-term health effects not directly related to the virus itself. In particular, research has found that even a mild case can cause long-term damage to the immune system, making a person more vulnerable to colds, flu, COVID-19, and other diseases for up to three years.

Scientists call this measles complication “immune amnesia” because it causes immune-system cells to “forget” their response to past infections from other pathogens.

“The measles virus resets immune cells so they only recognize the measles virus,” says Catherine Troisi, PhD, a professor of management, policy, and community health and epidemiology at the UTHealth Houston School of Public Health in Texas. This leaves a person unprotected against other infections in the aftermath, she notes.

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Experts Worry About a Rise in Flu, Diphtheria, and Tuberculosis

Over the years that doctors have been treating measles, they noticed that children who had the disease seemed more likely to get sick with other illnesses, says Aaron Milstone, MD, a professor of pediatric infectious diseases at Johns Hopkins Medicine in Baltimore.

It’s only been during the past 13 years that research has confirmed that measles impairs overall immunity — and scientists are still trying to figure out how.

Immune amnesia makes the current outbreak all the more troubling, as the rise in measles cases may lead to a spike of other dangerous infections such as flu, diphtheria, and tuberculosis.

“It’s just one more reason to get vaccinated for measles,” says Dr. Milstone. “The measles vaccine prevents immune amnesia, it’s safe, and the benefits far outweigh any risks.”

Immunity Can Dip Even for Those Immunized for Flu and Other Pathogens

In general, the human immune system has a remarkable ability to respond rapidly and effectively to bacteria and viruses that it has previously encountered.

Vaccines can help our immune systems by building long-lasting memory against specific pathogens (the agents that cause disease).

Still, people who have been vaccinated for flu, mumps, and other viruses may find that getting sick with measles weakens their immune defenses.

A study in ferrets found that those vaccinated against flu experienced a reduced level of flu antibodies after being infected with a measles-like virus.

Based on these results, the researchers concluded that measles could reverse the effects of vaccination against other infectious diseases.

“Measles seems to knock out naturally induced immunity as well as vaccine-induced immunity,” says Dr. Troisi. “But it’s also important to stress that the measles vaccine itself will not cause immune amnesia — it will prevent this from happening.”

How to Strengthen the Immune System

A study led by scientists at Princeton University suggested that individuals can regain their immune defenses to some viruses over the course of two to three years from gradual reexposure.

People who get measles may also benefit from immunization or re-immunization against common viruses, as well as booster shots of routine vaccines, such as hepatitis and polio.

“If you’ve had measles, I would certainly talk to your healthcare provider about getting revaccinated or vaccinated for preventable diseases other than measles,” says Troisi.

Milstone warns, however, that vaccines do not exist to protect against some viruses, such as norovirus.

A nutritious diet
Regular exercise
A healthy weight
Sufficient sleep

The Best Way to Avoid Immune Amnesia

Milstone emphasizes that the number-one way to avoid immune amnesia is to get the measles shot or vaccinate your kids if they haven’t been immunized already.

“Measles is spreading in the United States, so the chance of being exposed to measles is higher now than it’s been in a while,” he says. “But the dangers and complications, including immune amnesia, are all avoidable through vaccination.”

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