Mumps vaccines are vaccines which prevent mumps. When given to a majority of the population they decrease complications at the population level. Effectiveness when 90% of a population is vaccinated is estimated at 85%. Two doses are required for long term prevention. The initial dose is recommended between the age of 12 and 18 months of age. The second dose is then typically given between two years and six years of age. Usage after exposure in those not already immune may be useful.