Measles vaccine in the People's Republic of China.

The strains of measles virus and the method used in the production of further attenuated live-virus vaccine in the People's Republic of China were studied. Observation of clinical reactions and serologic responses to immunization with Shanghai-191 measles vaccine, which is produced on a large scale with a locally isolated viral strain, revealed that this vaccine is adequately safe and immunogenic. Epidemiologic data showed a significant decrease in measles-associated morbidity after the introduction of mass vaccination in 1965. The duration of immunity induced by Shanghai-191 measles vaccine was studied for eight years in a region in which interference due to natural measles infection had been minimized by mass vaccination of children. Although immunity appeared to persist for at least eight years, the results suggested that primary vaccination does not confer lifelong immunity. Reactions and antibody responses to this vaccine were compared with those to two vaccines from abroad, the Schwarz and Leningrad-16 strains. The hemagglutination-inhibiting (HAI) antibody titer induced by Shanghai-191 vaccine was higher than that induced by Leningrad-16 vaccine and lower than that induced by Schwarz vaccine; however, these differences were not significant. Preliminary studies on the preparation of measles vaccine in human diploid cells have yielded promising results.