Results of studying a live mumps vaccine from strain L-3 manufactured by the Moscow Research Institute of Viral Preparations. The reactogenic and antigenic properties of the vaccine]

The reactogenic and antigenic properties of live mumps vaccine from the L-3 strain were studied in 1507 children of 1 to 12 years of age. A single injection was given, one immunizing dose containing 10(4)HAdU50 of mumps virus. The live mumps vaccine from the L-3 strain irrespective of the lot of preparation, kind (live or lyophilized), method of application (jet-injector or needle/syringe), age of the vaccinees and the amount of virus in the immunizing dose received by a vaccinee, was demonstrated to be practically areactogenic and markedly antigenic. Serological examinations by neutralization tests of 346 paired serum specimens established variation in seroconversion between individual lots to be within 62.5--82.3% (average 69.9%) of cases. Comparative studies on the postvaccination and postinfection immunitiy in mumps showed the level of antibody in the vaccinees to vary within 4.2--5.1 log2 in different years, and in convalescents within 5.1--5.9 log2 in the same years. The results indicate a sufficiently high and intensive immunity for 5 years (the observation period).