Live measles vaccine: a 21 year follow up.

Abstract

21 years after receiving Schwartz strain live measles vaccine 4500 trial participants showed a continuing high level of protection compared with those who were unvaccinated. Over the last seven years of the follow up no cases of measles were reported in vaccinated participants who had had close contact with the disease. Immunity induced by the vaccine seems to survive the challenge of close contact with measles in young children, even after 21 years.