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COVID-19 vaccine effectiveness

The reason we vaccinate for COVID-19 is to reduce the risk of people becoming very sick if they catch the virus.

People who have received a COVID-19 vaccine have a much lower chance of developing more serious symptoms from COVID-19 or needing hospital treatment compared to those who did not get the vaccine.

All COVID-19 vaccines approved in Australia have been proven to be effective in reducing the risk of serious effects of COVID-19. ATAGI reports show that the relative short-term effectiveness of the vaccines against symptomatic COVID-19 infection after two doses is:

  • Moderna (Spikevax) vaccine over 90%
  • Pfizer (Comirnaty) vaccine over 90%
  • Novavax (Nuvaxovid) vaccine around 90%
  • AstraZeneca (Vaxzevria) vaccine over 70%.

Booster doses are recommended 3 months after you receive your second vaccine and then as recommended by ATAGI, which will make your vaccination more effective for a longer period of time.

Ongoing studies into effectiveness

You can find current information about studies and trials looking at the effectiveness of COVID-19 vaccines on the Australian Department of Health and the Therapeutic Goods Administration websites.

Other health measures to prevent sickness and stop the spread

Even though the COVID-19 vaccines work very well, no vaccine is 100% effective. It is still possible to catch COVID-19 after you have been vaccinated. That’s why it’s important that you still maintain physical distancing, practise good hygiene, wear a mask when necessary and follow current restrictions.

New variants

Viruses like SARS-CoV-2, which causes COVID-19, often change over time as they adapt to their environment. A new version of the virus is called a new ‘variant’ or ‘strain’. These changes in the virus can affect how well vaccines work.

Clinical trials looking into our current COVID-19 vaccines suggest that the vaccines will provide protection to a variety of mutations and minor virus changes. Sometimes, the antibodies (immune response) your body produced in response to the vaccine might be less effective against a particular strain. This information is still emerging and being reviewed often.

In the same way that the influenza (flu) vaccines change each season, the technology used to create the COVID-19 vaccines may be able to be adapted to changes in variants. For now, it is important that you get vaccinated to provide you with as much protection as possible against COVID-19.

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Safe, effective COVID-19 vaccines will offer protection against the virus, helping to prevent death and serious illness.

But how do they actually work?

Like other vaccines, such as the flu shot, COVID-19 vaccines will be given with a needle.

This triggers an immune response in the body – which is the body’s natural way of defending itself.

The vaccine will strengthen your immune system by training it to recognise and fight against the virus that causes COVID-19.

Vaccines may contain either killed or weakened versions of the virus that causes the disease – or a small part of the virus, such as a protein.

There is no risk that you will get the disease from a vaccine.

When your immune system recognises this virus, or parts of it, in the vaccine as being foreign, it responds by creating memory cells and antibodies that will protect you against future infection or disease.

As a result, you will be less likely to have severe COVID-19 symptoms after a vaccination.

To learn more, visit health.gov.au