The best time to have the vaccine is at the beginning of winter, in March or April. However there is no cut-off date for 'flu vaccination; it can be given at any stage during the winter.

It is usually given in one dose as an injection into the muscle.

Children younger than three years old receive half the adult dose. If children under nine years old have not had the vaccine before, they should receive a second vaccination one month later.

People travelling to the opposite hemisphere in that hemisphere’s winter should consider being vaccinated beforehand or on arrival.

Reviewed (2006) by Dr Jane Yeats MBChB, BSc(Med)(Hons)Biochem, FCPathSA(Virology).