Measles erased up to 73 percent of old antibodies

Researchers at Harvard Medical School and Brigham and Women's Hospital tracked antibody levels in 77 unvaccinated children before and two months after a natural measles infection, using a test called VirScan that reads antibodies against thousands of pathogens at once.

Measles wiped out 11 to 73 percent of each child's existing antibody repertoire, depending on the child, removing antibodies built against infections they had previously fought off. Children vaccinated against measles, mumps and rubella showed no such loss, and the same antibody wipeout was confirmed separately in measles-infected macaques.

Antibody levels partly recovered as children were naturally re-exposed to pathogens afterward, but the recovery was gradual, not immediate. The finding helps explain epidemiological data showing that measles is followed by two to three years of higher childhood deaths from other infections, deaths that fell when measles vaccination arrived.

One infection quietly reset years of immune memory.