» Measles Virus Vaccine Live conforms to the regulations of the FDA concerning biologics (630.30 to 630.37) (see Biologics 1041). It is a bacterially sterile preparation of live virus derived from a strain of measles virus tested for neurovirulence in monkeys, for safety, and for immunogenicity, free from all demonstrable viable microbial agents except unavoidable bacteriophage, and found suitable for human immunization. The strain is grown for purposes of vaccine production on chicken embryo primary cell tissue cultures derived from pathogen-free flocks and meets the requirements of the specific safety tests in adult and suckling mice; the requirements of the tests in monkey kidney, chicken embryo and human tissue cell cultures and embryonated eggs; and the requirements of the tests for absence of Mycobacterium tuberculosis and of avian leucosis, unless the production cultures were derived from certified avian leucosis-free sources and the control fluids were tested for avian leucosis. The strain cultures are treated to remove all intact tissue cells. The Vaccine meets the requirements of the specific tissue culture test for live virus titer, in a single immunizing dose, of not less than the equivalent of 1000 TCID50 (quantity of virus estimated to infect 50% of inoculated cultures × 1000) when tested in parallel with the U. S. Reference Measles Virus, Live Attenuated. It may contain suitable antimicrobial agents.