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The 'flu' vaccine: how it's made and how it works

Tuesday 11 April 2017

A woman sits on the couch blowing her nose, hand to her head, feeling sick.
The flu vaccine is reformulated each year to provide protection against the most prevalent strains of flu for the coming season.

Have you been wondering if you should bother getting vaccinated? Did you know that the influenza vaccine isn’t the same every year? Or that getting vaccinated each year provides the best protection against the flu?

Read on to learn what the flu is, how the vaccine works and why you should think about getting vaccinated this year.

What is influenza?

Influenza is a respiratory illness commonly known as ‘the flu’. Typical flu symptoms include fever, cough, muscle aches and pains, nasal congestion, headache, sore throat and fatigue.

While most people recover from the flu in about a week, sometimes the flu can lead to other serious health problems like bronchitis or pneumonia, or make a person’s existing health problems worse. Complications from the flu can be deadly: on average the flu causes an estimated 3,500 deaths in Australia each year.

Influenza is caused by a virus, which is a tiny infectious germ that hosts itself on another living organism’s cells. Influenza viruses are classified into different types and sub-types. Influenza A and B are responsible for the majority of illness in humans.

Influenza A viruses are divided into sub-types and those currently circulating among humans are A(HINI) and A(H3N2). Influenza B viruses are divided into two main groups, referred to as B/Yamagata and B/Victoria. Different strains dominate each year. Some strains may be more severe in certain age groups. For example the dominant strain in 2016 was H3N2 and this had a greater impact on older age groups.

Influenza viruses can evolve and mutate allowing new strains to emerge to which people may not be immune.

How is the flu vaccine made?

In February and September each year, The World Health Organization (WHO) holds a conference with leading experts and influenza centres from around the world to make recommendations about the composition of the next season’s flu vaccine.

They look at all the current information about influenza, including the recent patterns of flu epidemics across the world, to decide which strains of flu are likely to be most common in the next flu season. Vaccines are created to protect against these strains, usually containing three or four strain vaccines.

For countries in the Southern Hemisphere, like Australia, the information from the September conference helps them plan for flu vaccines for the following winter. After the conference, the Australian Influenza Vaccine Committee meet with the Therapeutic Goods Administration to confirm which strains will be included in the Australian flu vaccines. The vaccine funded for the National Immunisation Program in Australia contains the two strains of Influenza A most commonly circulating and the two Influenza B strains.

These vaccines then need to be made. It’s a long and time consuming process, with large amounts of each virus strain needing to be created to make enough vaccine doses.

A group of people of diverse ethnicity and ages stands together in a park, arms linked.

Why should I get a flu vaccine?

The flu is highly contagious, spreading when an infected person coughs or sneezes.  Droplets containing the influenza virus also settle onto surfaces, such as telephones and door knobs, and can then pass from hands to the nose, mouth or eyes. People with influenza can be infectious to others from 24 hours before they display symptoms until a week after the start of symptoms.

It’s recommended that all Australians over six months of age get a flu vaccine each year.

They should have the vaccine for two reasons:

  • To stop themselves from getting ill and;
  • To limit the spread of the virus to others in the community, particularly those most vulnerable to infection.

In Australia, the vaccine is provided for free for people aged 65 years and over, pregnant women, Aboriginal and Torres Strait Islander children and adults, and people with certain medical conditions which increase the risk of complications from influenza such as severe asthma, lung or heart disease, low immunity or diabetes.

It’s important to get a flu shot every year as the circulating virus strains change.  Receiving the vaccine from April allows protection from the flu to develop well ahead of the peak transmission period, which usually falls around July and August.

Last updated: 23 August 2017