Clinical trial of live measles vaccine given alone and live vaccine preceded by killed vaccine. Fourth report to the medical research council by the measles sub-committee of the committee on development of vaccines and immunisation procedures.

Follow-up of 5000 children given a single dose of live attenuated measles vaccine (Schwarz strain) when aged 10 months to 2 years shows a high level of protection in comparison with an unvaccinated group. This protection has been maintained for 12 years. Measles in vaccinated children was less severe as well as less frequent throughout the period. There is no evidence from the follow-up so far that a further injection of vaccine is needed; this has been confirmed by measles haemagglutination-inhibiting antibody estimations in a sample of the children.