ABSTRACT
Background: Measles vaccine was the only vaccine in the expanded vaccination program still must be imported. Center for research and production of vaccines and biologicals \ufffd?Ha Noi was conducting the first stages of measles vaccine manufacturing technology transfer from the Kitasato Institute in Japan. The Center received semi-finished vaccine to set up finished vaccine production process as well as the testing process. Potency test and its consistency is very essential in quality control. Objectives: In order to identify standard potency assessment methods and potency of 13 lots of finished measles vaccine produced in Viet Nam from imported semi-finished products. Subjects and method: 13 lots of the finished vaccine were determined potency by plaque method based on 13 samples of semi-finished vaccine and the standard sample M16-6 had potency from 4.2 to 4.6 lg PFU/0.5 ml provided by the Kitasato Institute. Results: The result of 13 lots show that the reduction of potency during freeze-drying is within the range (0-0.76 lg); and 4 last consecutive lots are met WHO criteria on heat stability. Conclusion: This shows that the measles vaccine freeze-drying process in Vietnam was officially set up to use for the measles vaccine production in 2007.