What is a live attenuated vaccine used for?

The weakened germ can stimulate an immune response that resembles protection after exposure, without behaving like the usual disease-causing form. Live attenuated vaccines are used in selected vaccination programmes, including some MMR, chickenpox and yellow fever vaccines.

Because the vaccine contains a living but weakened germ, it is not suitable for everyone. Age, pregnancy, immune-system function, medicines and recent vaccinations can affect whether it is advised.

Before vaccination, tell the clinician if you are pregnant, planning pregnancy, have an immune-system condition, take immune-suppressing medicine or have had a serious vaccine reaction. Bring your vaccination record so the schedule can be checked.

After the dose, mild soreness, tiredness or fever may occur. Follow the clinic's advice and attend any follow-up dose. Do not assume that a vaccine type is suitable based only on its name.

Get urgent medical help for trouble breathing, swelling of the face or throat, widespread hives, fainting or sudden severe illness after vaccination. Contact a clinician about persistent fever, unusual weakness or symptoms that are worsening.

Ask which vaccine is recommended, why a live attenuated option is appropriate or unsuitable for you, whether a dose should be delayed and which reactions need medical attention.