Measles wipes out the immune system's memory of previous illnesses, new research shows. Scientists have discovered that after suffering a bout of measles, youngsters are more vulnerable to other germs such as influenza or streptococci. The research revealed that the measles virus erases much of the immune system's memory of prior infections, hampering its ability to quickly react if those germs return. Scientists called the phenomenon "immune amnesia". Harvard researchers tested blood samples of unvaccinated Dutch children taken before and after a measles outbreak. After recovering from measles, the children's previous immunity to other germs dropped significantly. British researchers supported the findings, concluding that measles essentially returns the immune system to a baby-like state. There is some evidence that it could take years to rebuild those defences. The research was published on Thursday in the journal <em>Science and Science Immunology.</em>