A history of rubella should therefore not be accepted without serological evidence of previous infection. The incubation period is 14-21 days, and the period of infectivity is from 1 week before until 4 days after the onset of the rash. Infection is spread by respiratory droplets. Some infected infants may appear normal at birth, but defects, especially sensorineural deafness, may be detected later. In 1992 and 1993, rubella epidemics were reported in those States where rubella was notifiable.
Outbreaks usually occur in spring and early summer.
Must be stored in the dry state at 2-8deg. C or colder and protected from light. The lyophilised vaccine should be reconstituted with the diluent supplied by the manufacturer and should be used within 1 hour after reconstitution, provided it has been kept cool and protected from sunlight. Reconstituted measles vaccine is very unstable and quickly loses potency at room temperature after reconstitution. C it is completely inactivated after 1 hour.