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SALT LAKE CITY — A little-known potential side effect of measles called "immune amnesia" is getting attention amid the outbreak of the viral illness.
As of March 6, the Centers for Disease Control and Prevention reports a total of 222 measles cases in 12 jurisdictions: Alaska, California, Florida, Georgia, Kentucky, New Jersey, New Mexico, New York City, Pennsylvania, Rhode Island, Texas and Washington. That's considerably more than was reported the week before.
But one of the possible consequences of measles hasn't received as much attention as public health officials would like. The name says it all. "Immune amnesia" is damage to the immune system that causes it to forget someone has previously had other illnesses. That raises the risk of being reinfected with something to which the body should actually have antibodies.
As the American Society for Microbiology reports, "Without memory of past infections, the immune system is less able to fight off pathogens. The problem is that sometimes pathogens are responsible for the immune amnesia. Measles virus — an incredibly contagious virus that is currently spreading in the U.S. and other regions — can trigger immune amnesia."
Researchers at Harvard Medical School and Brigham and Women's Hospital found several years ago that measles can wipe out between 11% and 73% of a person's antibodies. Those are protective when it comes to getting the same illness again.
Or, as BBC put it, "Scientists have known for years that measles can alter the immune system — but the latest evidence suggests it's less of a mild tweaking and more of a total reset."
Outbreaks and growing concern
Measles is a resurging worldwide issue. The BBC reported that the number of measles cases reported in Europe in 2023, for instance, was 45 times higher than in 2022.
The viral illness is very contagious. People can be infected two hours after someone who has the illness leaves the area after coughing or sneezing or contaminating surfaces.
Symptoms range from high fever, runny eyes and nose and general misery to serious complications and even death. The CDC says 20% of those in the U.S. who get infected need to be hospitalized. And lasting consequences, "including brain damage and vision and hearing loss," among others, are possible.
The public health agency said that there have now been two deaths believed to be connected to measles. One case of a child in Texas has been directly linked to measles and the other, in New Mexico, is being investigated, though it is known that the individual tested positive for measles.
Previously infected? Forget about it
Dr. Céline Gounder, CBS News medical contributor and editor-at-large for public health at KFF Health News, told "CBS Mornings" that the ability of measles to block the immune system's memory can last months to a couple of years.
"It really does set a child back," she said. "Before kids were being vaccinated for measles, it's estimated that half of the deaths were actually from other infections they got later because of that weakened immune system."
While measles infection eventually loses its power to wipe immune memory, the lost memory is simply gone. Colds, flu, COVID-19 and even vaccinations you've had before contracting measles may disappear. Per the BBC, "The loss is near-total and permanent. Once the measles infection is over, current evidence suggests your body has to re-learn what's good and what's bad almost from scratch."
"In a way, infection of the measles virus basically sets the immune system to default mode," Mansour Haeryfar, a professor of immunology at Western University, Canada, said in the article, "as if it has never encountered any microbes in the past."
Research says measles does not wipe out memory of its own visit, however.
Harvard researchers explained how the memory wipe works: "If a person had 100 different antibodies against chicken pox before contracting measles, they might emerge from having measles with only 50, cutting their chicken pox protection in half. That protection could dip even lower if some of the antibodies lost are potent defenses known as neutralizing antibodies."
One of the Harvard scientists, Michael Mina, an assistant professor of epidemiology, created an analogy to explain the effect. Picture immunity from pathogens as a book full of photos of criminals you'd like to locate. But someone punched holes in those pictures. "It would then be much harder to recognize that criminal if you saw them, especially if the holes are punched over important features for recognition, like the eyes or mouth," he said.
Immune amnesia is of global concern. For instance, last August, Sri Lanka's Epidemiology Unit in the Ministry of Health called it a form of "extended immunosuppression."
Per that bulletin, the measles virus primarily targets alveolar macrophages in the lungs and a type of receptor that makes it easier for the virus to get into cells, where it releases viral genetic material into the cell. The infection is carried to the lymph nodes where it infects and destroys T-cells and B-cells to obliterate memory of preexisting immunity to illness. For two or three years, that memory-suppressing work continues, creating risk for infections.
The article said that after a child is infected with measles and recovers, routine childhood vaccines should be done over to be sure that they will protect the child.
Advice to vaccinate
The Sri Lanka bulletin's conclusion contains a plea: "The fight against measles is not merely a battle against a single disease; it is a fight to maintain the integrity of our immune systems and, by extension, the health of future generations."
Health experts are urging people to be vaccinated against measles if they are not already. The World Health Organization reports that measles killed an average of 2.6 million people each year before a vaccine was created. Even now, amid a decrease in access worldwide and lower uptake in some communities, 7 million people are infected and more than 100,000 die worldwide.
Utah is among states that have no case of measles this year, but both Utah state and Salt Lake County health officials have issued news releases encouraging people to take precautions against measles, including ensuring that children are current on their mumps, measles and rubella vaccination. Utah is among the states that allow exemptions. The Utah Department of Health and Human Services reports that Utah kindergartners are below the 95% vaccination rate needed to confer herd immunity and make it harder for the virus to spread to those who are not vaccinated.
