Among the unvaccinated, one in five people who get measles in the US will be hospitalised; one in twenty children will get pneumonia; one in a thousand will develop encephalitis, which can lead to blindness, hearing impairment and other disabilities; and one in a thousand will die. Measles can also lead to immune amnesia: that is, the virus can erase the body’s memory of how to fight all the pathogens it has previously encountered.

