True about measles outbreak ?

Ans. is 'c' i.e., Vaccination given at 6 months Epidemic of measles occur if propoion of susceptible children is > 40%. If measles is introduced in a virgin community, it infects > 90% of children. Measles vaccine is given at the age of a months, but age can be lowered to 6 months in epidemics. Measles shows a cyclic trend with epidemic every 2-3 years.