Influenza, commonly known as the flu, is caused by a highly contagious virus that is spread by contact with fluids from coughs and sneezes. Every year, the flu causes widespread illness in the community. Annual immunisation is recommended for older people and other people who are at risk of serious complications from the flu, such as pneumonia.
An influenza epidemic occurs when an outbreak of the illness is widespread in a certain community. A pandemic occurs when the illness is more geographically widespread and on more than one continent. Influenza epidemics occur, on average, every three years whereas pandemics have occurred only four times in the past 100 years.
Annual immunisation against the latest version of the flu is strongly recommended for people in at-risk groups such as older people, pregnant women, Aboriginal and Torres Strait Islander people, people with an underlying medical condition and those who work or live with people in at-risk groups. Serious side effects or allergic reactions to the vaccine are rare. If you are concerned about your reaction or your child's reaction to any vaccine, see your doctor immediately.
Immunisation against the flu
Immunisation of people who are at risk of complications from the flu is the most effective way to reduce the number of flu infections and deaths.
Influenza viruses change every year because the influenza virus has a unique ability to change its surface structure. This means that even if you had the flu or an immunisation one year, your body's immune system might be unable to fight the changed version of the virus that is circulating the following year.
Each year, a new vaccine is developed (usually called the seasonal vaccine) and is available for those who wish to be immunised. Ideally immunisation should occur in autumn, before the onset of the flu season. Protection develops about two weeks after the injection and lasts for up to one year. Most cases of influenza occur within a six- to eight-week period during winter and spring.
The influenza vaccine cannot give you a dose of flu because it does not contain live virus. Some people may still contract the flu because the vaccine may not always protect against all strains of the influenza virus circulating in the community.
Vaccination experts recommend the flu vaccine for everyone from six months of age, however the vaccine is only free under the National Immunisation Program for people at high risk of complications, including:
- pregnant women
- Aboriginal and Torres Strait Islander people
- people aged 65 years and over
- people with certain medical conditions.
Pregnant women are at higher risk of severe complications associated with the flu. Vaccinating against flu at any stage during pregnancy also provides some protection for babies during their first, vulnerable months of life.
Aboriginal and Torres Strait Islander people
All Aboriginal and Torres Strait Islander people from six months to less than five years of age, and 15 years of age and over, are eligible for free flu vaccination.
People 65 years and over
People aged 65 years and over have the highest risk of complications associated with seasonal flu.
People with certain medical conditions
People with some existing medical conditions are more likely to experience complications from flu. Free flu vaccinations are available for people aged six months and over who have:
- heart disease
- severe asthma
- chronic lung condition
- chronic illness requiring medical follow-up or hospitalisation in the past year
- diseases of the nervous system
- impaired immunity
Children aged six months to 10 years who are on long-term aspirin therapy are also eligible.
Contact your doctor or immunisation provider for further information about eligibility. People not covered by these categories can also have an annual flu immunisation but it is not available for free.
People who work or live with people with certain medical conditions
Immunisation is also recommended (but is not necessarily free) for people who can put vulnerable people at risk of infection. People who work with or live in close contact with people who have an underlying medical condition or impaired immunity should also be immunised to minimise the spread of the flu to themselves, the people they work or live with and their families. These people include:
- public and private hospital staff who provide direct care to people
- staff in long-term care facilities or nursing homes
- people who live with, or care for, someone who has a chronic illness or is aged over 65 years
- carers of homeless people
- workers, particularly those in workplaces that provide essential services
- people who work with children
- people involved in the commercial poultry and pig industry
- workers in other high-risk industries
- anyone visiting parts of the world where flu is circulating, especially if travelling in a group.
Some workplaces run annual immunisation programs for staff.
Pre-immunisation checklist for the flu vaccine
Before receiving the vaccine, make sure that you tell your doctor or nurse if you (or your child):
- are unwell (have a temperature over 38.5˚C)
- have allergies to any other medications or substances
- have had a serious reaction to any vaccine
- have had a serious reaction to any component of the vaccine
- have had a severe allergy to anything
- have had an severe allergy reaction to eggs – the virus used in the vaccine is grown in eggs
- have had Guillain-Barré acute syndrome.
You should also tell your doctor or nurse if your child is under six months old.
Side effects of the flu vaccine
The flu vaccine can cause a range of side effects. In children under five years of age, these reactions may be more obvious. Common side effects of flu vaccine include:
- drowsiness or tiredness
- muscle aches
- localised pain, redness and swelling at the injection site
- occasionally, an injection-site lump (nodule) that may last many weeks but needs no treatment
- low-grade temperature (fever).
Managing fever after immunisation
Common side effects following immunisation are usually mild and temporary (occurring in the first few days after vaccination). Specific treatment is not usually required. There are a number of treatment options that can reduce the side effects of the vaccine including:
- drinking extra fluids and not overdressing if there is a fever
- although routine use of paracetamol after vaccination is not recommended, if fever is present, paracetamol can be given – check the label for the correct dose or speak with your pharmacist, (especially when giving paracetamol to children)
Concerns about side effects
If the side effect following immunisation is unexpected, persistent or severe, or if you are worried about yourself or your child's condition after a vaccination, see your doctor or immunisation nurse as soon as possible or go directly to a hospital.
Immunisation side effects may be reported to the Victorian Vaccine Safety Service, the central reporting service in Victoria on 1300 882 924 (option 1). You can discuss how to report problems in other states or territories with your immunisation provider. It is also important to seek medical advice if you (or your child) are unwell, as this may be due to other illness rather than because of the immunisation.
Rare side effects of the flu vaccine
There is a very small risk of a serious allergic reaction (anaphylaxis) to any vaccine. This is why you are advised to stay at the clinic or medical surgery for at least 15 minutes following vaccination in case further treatment is required. Apart from anaphylaxis, other extremely rare side effects include febrile convulsions in children.
In 2010, one brand of influenza vaccine caused an increase in fever and febrile convulsions in very young children under five years of age. This brand is no longer registered for use in young children. Your doctor will discuss with you the best influenza vaccine brand for your child.
Immunisation and HALO
The immunisations you may need are decided by your health, age, lifestyle and occupation. Together, these factors are referred to as HALO.
Talk to your doctor or immunisation provider if you think you or someone in your care has health, age, lifestyle or occupation factors that could mean immunisation is necessary. You can check your immunisation HALO using the Immunisation for Life infographic.
Where to get help
- Your doctor
- In an emergency, always call triple zero (000)
- Emergency department of your nearest hospital
- Your local government immunisation service
- Maternal and Child Health Line (24 hours) Tel. 132 229
- NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice (24 hours, 7 days)
- Immunisation Section, Department of Health and Human Services, Victorian Government Tel. 1300 882 008
- National Immunisation Information Line Tel. 1800 671 811
- Victorian Vaccine Safety Service, Victorian Vaccine Education Centre Tel. 1300 882 924 (option 1) between 9 am and 4 pm – you can leave a message at all other times
Things to remember
- Influenza is a viral disease that causes widespread illness every year.
- Immunising people who are at risk of complications from the flu is the most effective way to reduce the number of flu infections and deaths.
- Influenza immunisation is recommended for people in known high-risk groups.
- People who work or live with people who are at risk of serious complications should also be immunised to avoid spreading the flu.
- The vaccine cannot give you a dose of flu because it does not contain any live virus.