How does MMR vaccination work?

The vaccine gives the immune system harmlessly weakened versions of the three viruses. Defence cells identify them and build antibodies and memory cells. If the body later encounters the viruses, this learned response can act more quickly and reduce the chance of illness or make illness less severe. The vaccine is a live attenuated vaccine, so it is different from a vaccine made with a completely inactive virus.

Protection develops after vaccination rather than immediately. Some people have a mild fever, a short-lived rash or soreness, because the immune system is responding. These effects are generally temporary and are not the same as having measles, mumps or rubella.

Tell the vaccinator about pregnancy, a weakened immune system, severe previous vaccine reactions and medicines that affect immunity. Bring your vaccination record if available so the recommended schedule can be checked. After the injection, stay for the observation period advised by the clinic and drink fluids as usual. Use a cool cloth for local soreness; seek advice before giving a child any medicine for fever.

Seek urgent help for trouble breathing, swelling of the face or throat, collapse or widespread hives soon after vaccination. Contact a clinician for a high or persistent fever, unusual drowsiness, a seizure, or a child who is not drinking. A rash or fever after MMR should be discussed if it is worsening or accompanied by other concerning symptoms; it does not by itself show that the vaccine caused measles.

Ask which doses are recommended for your age and circumstances, whether any health condition changes the timing, and what symptoms should prompt a call. You can also ask how MMR vaccination helps prevent measles, mumps and rubella and whether your record needs updating.