People who are not vaccinated, or who have received only one dose, run a high risk of disease, because measles can easily be caught through direct contact and droplets that spread through the air.

Measles is one of the most contagious of the vaccine-preventable diseases. This means that to stop it from being transmitted, the highest levels of immunity must be maintained.

Normally, the measles, mumps and rubella (MMR) vaccine, containing a weakened live virus, is given to children in two doses, the first at 12-15 months and the second at 4-6 years of age. All children are required to receive the two doses of the MMR vaccine before starting school.