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 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 important way we have 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 will be 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. In Victoria, the 2013 seasonal influenza vaccine includes protection against two strains of influenza A (H1N1 and H3N2) and one strain of influenza B.
Immunisation should occur between March and May, 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.
An annual flu immunisation is provided through the National Immunisation Program for most people in the community who are considered to be at an increased risk of complications. In Victoria, an annual immunisation against the flu is free for:
- people six months and over who have medical conditions that put them at risk of serious complications of the flu
- Aboriginal and Torres Strait Islander people aged six months to under five years and 15 years and over
- pregnant women – at any stage of pregnancy
- people 65 years and over.
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 should be immunised against the flu
People with an underlying medical condition or reduced immunity are most at risk and should be immunised. They include:
anyone aged 65 years and older
pregnant women (at any stage of pregnancy)
Aboriginal and Torres Strait Islander people aged six months to under five years and 15 years and over
people aged six months or older with heart disease, chronic lung disease, chronic neurological conditions, Down syndrome, impaired immunity or haemoglobinopathies (blood disorders caused by genetic changes)
people with other chronic conditions such as obesity, alcoholism, diabetes and kidney disease
residents in nursing homes or other long-term care facilities
people who are homeless
people with severe asthma who require frequent hospital visits
children on long-term aspirin therapy
other chronic illnesses requiring regular medical follow-up or hospitalisation.
Immunisation is also recommended (but 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.
Pregnancy and immunisation
Influenza vaccine is recommended for women planning a pregnancy and it is safe for pregnant women at anytime during the pregnancy or while breastfeeding.
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
- are under six months of age
- have had Guillain-Barré syndrome.
Side effects of the flu vaccine
The influenza 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 (03) 9345 4143. 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. A small increase in Guillain-Barré syndrome was seen in the US in 1976, but since that time, surveillance has shown that it is limited to one case for every million doses of flu vaccine, if at all.
If any other reactions are severe and persistent, or if you are worried, contact your doctor for further information.
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 downloadable poster (pdf).
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 Program, Department of Health, Victorian Government Tel. 1300 882 008
- National Immunisation Information Line Tel. 1800 671 811
- Victorian vaccine safety service Tel. (03) 9345 4143 – the line is attended between 10 am and 3.30 pm and 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 important way we have 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.