Abstract

A natural infection with measles generally gives lifelong immunity. Panum’s classical observation that elderly people in the Faroes, who had developed measles in an epidemic in 1781, did not have the illness in the next outbreak in 1846, suggests that this permanent immunity does not depend upon repeated exposure to the virus. Whether measles vaccine will give immunity of comparable duration is an important question, since temporary immunity might only postpone the natural infection to adulthood. Not much is known about the severity and consequences of measles infection in adults except in special circumstances when serious results have followed introduction of the virus to virgin populations. Moreover, eradication of measles will be difficult to achieve if vaccine immunity is of limited duration.