Results from tests of unvaccinated children and monkeys come as measles cases spike around the world.
Measles infections in children can wipe out the immune system’s memory of other illnesses such as influenza, according to a pair of studies1,2. This can leave kids who recover from measles vulnerable to other pathogens that they might have been protected from before their bout with the virus.
The findings, published on 31 October in Science and Science Immunology, come at a time when measles cases are spiking around the world. Globally, there were more measles infections in the first six months of 2019 than in any year since 2006, according to the World Health Organization.
The studies highlight the importance of measles vaccinations, says Michael Mina, an infectious-disease immunologist at the Harvard T. H. Chan School of Public Health in Boston, Massachusetts, and a co-author of the Science paper.
The measles virus is highly contagious, and can lead to complications including pneumonia. And previous studies have suggested that the virus induces a kind of forgetfulness in the immune system, says Duane Wesemann, an immunologist at Brigham and Women’s Hospital in Boston. When people get an infection, their immune system creates antibodies to fight it off. Once the body clears the infection, special immune cells remember that pathogen and help to mount a faster defence if the virus or bacterium invades again.
The Science study is the first to show definitive evidence that measles can destroy this immune memory, Mina says.
Mina and his colleagues analysed blood samples from 77 unvaccinated children from 3 schools in the Netherlands, taken before and after a measles outbreak in 2013. The team also collected blood samples from 33 children before and after their first vaccination against measles, mumps and rubella (MMR). The researchers analysed the kids’ antibodies using a test that measures the amount, and the strength, of antibodies against thousands of viral and bacterial substances.
Two months after the unvaccinated children recovered from measles, the team found that the virus had erased 11–73% of their antibodies against other bacteria and viruses. Although the reasons behind the high variability in antibody reduction are unclear, the finding shows that the virus alters previously acquired immune memory, Mina says. The kids who received the MMR vaccine showed no reduction in these antibodies.[…]