Are vaccines safe?

Find information about vaccine testing, ingredients, side effects, and more.

Vaccine testing

Research and testing is an essential part of developing safe and effective vaccines.

In Australia, every vaccine must pass strict safety testing before the Therapeutic Goods Administration (TGA) will register it for use.

Before vaccines become available to the public, they are tested on thousands of people who take part in large clinical trials.

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How are vaccines shown to be safe? fact sheet

A fact sheet about how vaccines are shown to be safe, noting how all vaccines are carefully tested.

Vaccine ingredients 

Each ingredient in a vaccine serves a specific purpose. For example, some ingredients help to keep the vaccine free from contaminants, and others allow the vaccine to provide better protection. Each ingredient is tested in the vaccine manufacturing process.

Vaccine ingredients vary depending on what the vaccine is used for. They may contain:

  • a very small dose of a live (but weakened) virus
  • killed viruses
  • killed bacteria
  • small parts of bacteria
  • a small dose of a modified toxin produced by bacteria
  • a small amount of preservative
  • a small amount of an antibiotic to preserve the vaccine.

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What is in vaccines? fact sheet

Fact sheet about vaccine ingredients, noting that all ingredients are tested for safety.

You can also search the TGA's product information for more detail about each vaccine and its specific ingredients.

Vaccine side effects

Your child may experience minor side effects following vaccination. Most side effects last no more than a couple of days and your child will recover without any problems. Mild reactions can be managed with simple steps, such as giving paracetamol.

Common reactions to vaccination include:

  • pain, redness and/or swelling where you received the needle
  • mild fever.

Serious reactions like allergic reactions are extremely rare. If you have a reaction that you think is severe or unexpected, seek medical advice straight away. 

If you have any concerns about potential side effects of vaccines, talk to your doctor or nurse.

Vaccine safety monitoring

The TGA and the company that makes the vaccine closely monitor how well a vaccine is working and how safe it is in the community.  

Vaccines are monitored and tested after their introduction in a number of ways, including:

  • further clinical trials
  • national surveillance
  • monitoring of serious side effects.

In Australia, clinicians who specialise in immunisation actively monitor people who have been vaccinated in a range of healthcare settings, including general practices, community clinics and hospitals to see if they have experienced any problems. This system is called AusVaxSafety
AusVaxSafety has captured information from hundreds of thousands of vaccination encounters across Australia. The data shows that the rates of adverse effects after vaccination are extremely low.

You can report adverse events directly to the TGA online using:

You can also report AEFIs to your state or territory health service.

Did you know?

We do not use mercury in vaccines anymore

Thiomersal which contains mercury was used as a preservative in some vaccines in very small amounts. Thiomersal was removed from all vaccines on Australia’s National Immunisation Program in 2000.

There is no scientific evidence the small amounts of the thiomersal used in vaccines caused any harmful effects in children or adults.

There is no established link between vaccines and autism

High quality studies over many years have compared the health of large numbers of vaccinated and unvaccinated children. Medical information from nearly 1.5 million children living around the world was able to confirm that vaccination does not cause autism.

The concern around autism and immunisation came from a paper published in The Lancet in 1998, claiming a link between the measles, mumps, rubella vaccine and autism. The paper has since been completely discredited and was withdrawn from the Lancet in 2010. The journal printed an apology after withdrawing the paper.

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Vaccination and autism fact sheet

This fact sheet explains how we know vaccination does not cause autism and where the misunderstanding came from.

Immunisation allergy and asthma

Wide and varied studies show no increase in allergy or asthma due to childhood vaccines.

Vaccination helps children with asthma or allergic disease. It helps them by reducing their likelihood of getting a serious infection, that could make their asthma or allergy symptoms worse.

If you’re concerned about your child’s allergies or asthma in relation to vaccination, speak to your doctor or immunisation provider.

Further information

You can find more information on vaccine safety in the following resources:

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