Influenza vaccine

Easy-to-read medicine information about influenza vaccine – what is it, how to get the influenza vaccine and possible side effects.

Type of medicine Also called
  • Vaccines
  • Seasonal 'flu' shot
  • Fluvax®
  • Influvac®
  • Vaxigrip®

What is influenza vaccine?

  • Influenza vaccine is used to prevent infection caused by the influenza ("flu") virus.
  • Influenza can cause serious illness, especially in people at high risk from the infection (such as young children, the elderly, and people with chronic health problems). 
  • Vaccination is the best method for preventing infection and reducing the seriousness of illness if you become infected. It will greatly improve your chances of not getting the flu, but it does not give 100% protection.
  • Vaccines work by causing the body to produce its own protection (antibodies) against the virus. The vaccine cannot cause influenza because it does not contain any active (live) viruses. 
  • Each year the flu vaccine is developed to match the different strains of flu virus you are likely to encounter. In New Zealand, the new vaccine is normally made available in early March and people are advised to have the vaccine before the winter season when the flu is most widespread.


Adults and children over 9 years

  • Only one dose of the vaccine is required to achieve protection for the season.

Children aged between six months and nine years

  • Two doses of the vaccine are required, with the second dose given at least four weeks after the first.
  • Children in this age group who have received an influenza vaccine at any time in the past require only one dose.

How and when is influenza vaccine given?

  • Influenza vaccine is given by injection into the muscle such as the muscle on your upper arm.
  • If you have a condition that makes you bleed more easily than normal, it may be given as an injection underneath your skin.
  • The vaccination is usually given in the time from March to June when the number of cases of influenza virus begins to increase (the start of "flu season").
  • It takes two weeks after vaccination for the vaccine to be fully effective.
  • You may still develop influenza in this time if you come into contact with the virus, so get it done early in time for winter.

Possible side effects

Like all medicines, the influenza vaccine can cause unwanted side effects, although not everyone gets them. Often unwanted side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Pain, swelling, or redness around the injection site 
  • This is quite common for the first 1 or 2 days after receiving the injection.
  • It usually settles after a few days.
  • Tell your doctor if troublesome.
  • Mild fever
  • Feeling unwell, tired or weak
  • Loss of appetite
  • Muscle ache
  • Headache
  • These are quite common for the first 1 or 2 days after receiving the injection.
  • It usually settles after a few days.
  • Tell your doctor if troublesome.
  • Signs of an allergic reaction such as skin rash, itching, blisters, peeling skin, swelling of the face, lips, mouth or have problems breathing
  • Allergic reactions to influenza vaccine are very rare.
  • If you develop these signs within a few days of the immunisation, tell your doctor immediately or ring HealthLine 0800 611 116.

Learn more

The following links provide further information on influenza vaccine. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Flu can be anywhere FightFlu, Ministry of Health NZ  
Influenza vaccine Patient Info, UK

Credits: Sandra Ponen, Pharmacist.