An introduction to vaccinations

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What are vaccinations?

Vaccinations improve immunity to particular diseases. They provide a safe and effective way of preventing the spread of many diseases that can cause significant health problems, including death. Vaccinations are considered to be the most significant public health intervention in the last 200 years.

People often use the terms vaccination and immunisation interchangeably, but there is a subtle difference. Essentially, a vaccination is when a vaccine is given to you, most commonly by injection. Immunisation is what occurs to your immune system as a result of the vaccination; it is the process of becoming immune to the disease.

How do vaccines work?

Vaccines typically contain an agent that closely resembles the bacteria or virus (microorganism) that causes the disease. This microorganism-resembling agent (called an ‘antigen’) stimulates the immune system into recognising it as foreign, destroying it and ‘remembering’ it. This ‘memory’ is particularly important, as this is what allows the body’s immune system to more easily recognise and destroy microorganisms it might be exposed to later.


Classifying vaccines

Vaccines can be broadly classified as live or inactivated.

Live vaccines

Live vaccines are developed using ‘wild’ microorganisms, which means that they are developed from microorganisms that are naturally occurring and disease-causing.  They have been weakened (referred to as ‘attenuated’) before being used in the vaccine. After vaccination, the ‘weakened’ microorganism grows in the body and stimulates an immune response.

Live vaccines do not usually cause disease in healthy people. In rare cases, they can cause a milder version of the disease.

Inactivated vaccines

Inactivated vaccines are made using microorganisms that were grown in a laboratory and then inactivated before being put in the vaccine. Nothing in an inactivated vaccine is alive, and after it is administered, the vaccine agent cannot grow or cause disease.

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Inactivated vaccines usually require multiple doses, as well as periodic doses called ‘boosters’ to increase protection against the disease.


What else is in a vaccine?

As well as containing the antigen (the agent resembling the bacteria or virus), vaccinations usually also contain a few other ingredients.


These help to strengthen the immune system’s response to the antigen. They are most commonly salts, such as aluminium hydroxide, aluminium sulphate and potassium aluminium sulphate.


These protect vaccines from becoming contaminated with unwanted bacteria of fungi. The most common preservative is a tiny amount of alcohol, not enough to have any effect on the body.


These are sugars or oils that prevent vaccines from going off, or sticking to the sides of the vaccine container.


These are substances that remain in the vaccine after the manufacturing process. These are harmless in the tiny amounts found in the vaccine, and most are already present in our bodies.


These are usually sterile or salt water, and they have no effect on the body whatsoever. They are included to help control the concentration of the vaccine.

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What is not in a vaccine?

Mercury is not found in vaccines given in Australia. Thiomersal, which is a salt that contains a tiny amount of mercury, is no longer used in Australia. It was removed from all vaccines in Australia’s National Immunisation Program in 2000.


Which diseases can we be vaccinated against?

The World Health Organization (WHO) lists 26 available vaccines. Each one combats a specific disease. In Australia, the standard vaccination schedule lists 17 different types of vaccinations, given at different ages, that combat 17 different diseases. Some of these vaccines exist in various combinations.

To learn more about which vaccines your child should receive at what age, see:

Certain vaccinations that fall outside the standard schedule are also commonly administered in Australia for ‘at risk’ groups, such as the flu vaccine.


What are the benefits of being vaccinated?

Vaccinations are a safe and effective way of giving protection against disease. Vaccinations not only protect you as an individual, but also your family and your community.

Since the introduction of vaccinations in 1932 for children in Australia, there has been a 99% reduction in deaths caused by vaccine-preventable diseases. Worldwide, WHO estimates that vaccines save 2-3 million lives every year.


What are the risks of being vaccinated?

Minor side effects to vaccinations are common, but generally last less than a couple of days with no lasting issues. Common reactions include pain, swelling and/or redness at the injection site, and mild fever. Serious reactions (such as an allergic reaction) are extremely rare.

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In Australia, every vaccine must undergo and pass strict safety testing before the Therapeutics Goods Administration (TGA) will allow its use. Furthermore, vaccination experts actively monitor the use of vaccines in the community, ensuring their ongoing safety.

Vaccines and autism

A large number of high quality studies have completely debunked the myth that vaccines cause autism.

This fraudulent claim resulted from a seriously flawed paper that was published in a medical journal in 1998, which linked the measles, mumps and rubella vaccine with autism. Since the time of publication, the paper has been completely discredited; importantly, the journal was quick to withdraw the paper, issuing a prompt apology.


What are the risks of not being vaccinated?

If your child contracts a vaccine-preventable disease, the consequences could be devastating.

It’s easy to get caught in the trap of thinking that vaccines only protect us from diseases that are no longer relevant in Australia. However, Australia has seen a significant increase in vaccine-preventable diseases over the past decade. In 2014 alone, there were over 100,000 cases of vaccine-preventable diseases. This included more than 11,000 cases of whooping cough, 340 cases of measles, 190 cases of mumps, 21 cases of invasive Haemophilus influenza type b infection, 17 cases of rubella, 3 cases of tetanus and 2 cases of diphtheria. It is hard to appreciate from these numbers just how fast some of these diseases can spread. Measles, for example, is so contagious that 9 out of 10 non-immune people who are in close contact with an infected person will catch the disease.

Furthermore, choosing not to vaccinate your child is a decision that not only affects your child, but also your community. When 95% or more of a population is vaccinated, the community will achieve the benefits of ‘herd immunity’ – when the level of immunity of the entire population is sufficient to prevent disease outbreaks. Herd immunity is important because it protects those who cannot be vaccinated, including those who are too young, those who cannot be vaccinated due to medical reasons, and those with suppressed immune systems (such as those on chemotherapy). When your child is vaccinated, they are helping to protect those around them as well as being protected themselves.


More information

For more information about vaccinations in pregnancy and in children in Australia, see Vaccinations.



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Date Created: May 31, 2018 Date Modified: June 7, 2018