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About the COVID-19 vaccines

17-minute read

The COVID-19 vaccine will be available to all Australians in 2021. Read about its safety, development, approval and more.

If you have severe difficulty breathing, call triple zero (000) immediately and tell the call handler and the paramedics on arrival about your recent travel history and any close contact with a person with confirmed COVID-19.

Which COVID-19 vaccines are available in Australia?

Australia’s Therapeutic Goods Administration (TGA) has provisionally approved vaccines for COVID-19:

  • COMIRNATY, the Pfizer-BioNTech COVID-19 vaccine, provisionally approved for people aged 12 years and older
  • COVID-19 Vaccine AstraZeneca, the Oxford University-AstraZeneca vaccine, provisionally approved for people aged 18 years and older
  • Janssen vaccine by Janssen-Cilag Pty Ltd, known as Johnson & Johnson, provisionally approved for people aged 18 years and older

Pfizer vaccine

The Pfizer vaccine, called Cominarty, is an mRNA vaccine. People need to receive 2 doses of Cominarty, given at least 21 days apart. The minimum acceptable interval between the 2 doses is 19 days. If this isn’t possible, it is recommended to complete the 2-dose course within 6 weeks.

It is not recommended to repeat a vaccine dose if the interval between doses is less than 19 days.

You can read the consumer medicines information leaflet (CMI) for this vaccine here.

The Australian Technical Advisory Group on Immunisation (ATAGI) recommends that Pfizer is the preferred vaccine for people aged 59 and under. (People aged 18 and over who've already had their first dose of the AstraZeneca vaccine without any adverse effects can have a second dose of AstraZeneca.)

AstraZeneca vaccine

The AstraZeneca vaccine, called COVID-19 Vaccine AstraZeneca, is a viral-vector vaccine. ATAGI recommends that AstraZeneca is the preferred vaccine for people aged 60 years and older. You can read the consumer medicines information leaflet (CMI) for the AstraZeneca vaccine here.

People also need to receive 2 doses of the AstraZeneca vaccine. The second dose should be given 4 to 12 weeks after the first dose.

In areas where there are no coronavirus outbreaks, ATAGI recommends that the preferred interval between doses of the AstraZeneca vaccine remains at 12 weeks. In areas where there is a significant COVID-19 outbreak involving the Delta variant:

  • an interval of between 4 and 8 weeks is preferred
  • it’s recommended that adults aged 59 and under who do not have immediate access to Pfizer’s Comirnaty vaccine reassess the benefits of vaccination with AstraZeneca versus the rare risk of a serious side effect

For more information, see, ‘Can I get the AstraZeneca vaccine?

Janssen vaccine

The COVID-19 vaccine Janssen is a viral vector vaccine and requires a single dose. This vaccine is not included in Australia’s COVID-19 vaccination program.

Other vaccines

The Australian Government also has agreements to secure the following vaccines:

  • Moderna — the Australian Government has signed an agreement for the supply of 25 million doses of the Moderna vaccine, Elasomeran. This vaccine is yet to be approved by the TGA (but has been granted a provisional determination — see below). It is likely that 2 doses will be required, 28 days apart.
  • Novavax — if approved by the TGA, it’s anticipated that 51 million doses will be available in Australia. You’ll likely need 2 doses.
  • COVAX facility — this is a global initiative that will provide access to COVID-19 vaccines when they become available. If approved, it’s anticipated that 25 million doses will be available to the Australian population.

The TGA has granted a provisional determination to Moderna Australia for its vaccine called Elasomeran. The first step in the approval process, this means that Moderna can submit an application to the TGA for provisional approval.

This will allow the TGA to conduct a thorough review of Elasomeran before deciding whether to give it provisional approval.

Why is Pfizer the preferred vaccine for people aged 59 and under?

There is a link between the AstraZeneca vaccine and a very rare condition called thrombosis with thrombocytopenia syndrome (TTS). The risk of this occurring is slightly higher in younger adults than in older adults. TTS typically occurs around 4 to 42 days after AstraZeneca vaccination and can be treated very effectively.

Therefore, the Australian Technical Advisory Group on Immunisation (ATAGI) recommends that Pfizer is the preferred vaccine for people aged 59 and under.

However, if you’re aged 18 to 59 years, you can have the AstraZeneca vaccine if you’ve weighed up the benefits and the risks, and you provide informed consent. This is regardless of whether you’re in a current eligibility group.

You can also choose to wait to get the Pfizer vaccination later in 2021, when the Pfizer vaccine is offered to more groups. Talk to your doctor or immunisation provider to help inform your decision.

Are COVID-19 vaccines safe?

All vaccines are thoroughly tested for safety before they’re approved by the Government’s therapeutic regulatory body, the Therapeutic Goods Administration (TGA), for use in Australia.

As part of the Australian Government’s Department of Health, the TGA is responsible for regulating all therapeutic goods, including prescription medicines, vaccines, sunscreens, vitamins and minerals, medical devices, blood and blood products. Testing involves carefully analysing clinical trial data, ingredients, manufacturing processes and other factors.

Even after you receive a vaccine, it’s still monitored for safety.

If you have any questions about vaccination, talk to your doctor, nurse or other healthcare professional. They can also give feedback to the TGA about any side effects — even if they’re minor. This will help the TGA oversee the safety of vaccines. In the unlikely event that a safety risk develops, the TGA will inform healthcare providers, the community and the Australian Government as soon as possible.

How are vaccines approved in Australia?

Before a COVID-19 vaccine becomes available in Australia, it must pass the rigorous approval processes of the Therapeutic Goods Administration (TGA). This includes assessing every ingredient in the vaccine for safety, quality and effectiveness.

A clinical trial is a scientific study conducted by the makers of a vaccine. Clinical trials of medicines are done in phases.

The TGA carefully assesses the results of clinical trials, as well as the way in which the trials were run. The TGA also checks that the trials involved enough human participants that represented the people for whom the vaccine is intended.

The TGA ensures that vaccine manufacturers meet manufacturing quality standards. TGA laboratories assess the quality of every batch of a vaccine before it can be supplied in Australia.

Sometimes a ‘provisional approval pathway’ is needed for the temporary registration of promising new medicines and vaccines — where the need for early access outweighs any risks.

The TGA has provisionally approved the Pfizer, AstraZeneca and Janssen vaccines. The Janssen vaccine is not yet included in Australia’s COVID-19 vaccination program.

It’s expected that other makers of COVID-19 vaccines will apply to the TGA for registration using this provisional approval pathway.

Video provided by Australian Government Department of Health

What is a vaccine?

Vaccination prepares the immune system to fight against a future infection. Vaccines often contain tiny amounts of dead or weakened viruses or bacteria, called antigens. The immune system responds to these antigens without you getting sick, effectively training the immune system to fight the disease if exposed to it in the future.

Some vaccines need to be given more than once — known as ‘booster’ vaccinations. Some vaccines, such as the seasonal influenza (flu) vaccine, only work for a short period of time. This is because the virus itself can change over time.

Vaccines are usually given with an injection.

Video provided by Australian Government Department of Health

What ingredients are in a vaccine?

The ingredients of a vaccine vary, depending on what the vaccine is for. A vaccine may contain some of these ingredients:

  • a protein component of a virus
  • a piece of genetic code (DNA or mRNA)
  • a very small dose of a weakened virus
  • a substance to boost the immune response (known as an adjuvant)
  • sterile salt water (saline) for injections
  • a small amount of preservative or stabilisers, which ensure vaccines stay effective during storage and transportation

Once a COVID-19 vaccine has been approved by the Therapeutic Goods Administration (TGA), its ingredients will be listed in the Australian Register of Therapeutic Goods.

How do different COVID-19 vaccines work?

Vaccines train your immune system to quickly recognise and get rid of the bacteria or viruses that can cause serious illnesses. There are many types of vaccine being developed to protect us against COVID-19. They’re all designed to generate an immune response specific to the COVID-19 coronavirus.

Most COVID-19 vaccines use the coronavirus ‘spike’ protein to cause this immune response. The immune system recognises this spike protein as ‘foreign’ and starts producing long-lasting immune cells and antibodies.

If a vaccinated person becomes exposed to COVID-19 later on, the immune system will be able to launch a faster and better response to protect against the disease.

Important: these vaccines do not contain the live or whole virus that causes COVID-19.

Here’s how the common types of COVID-19 vaccine work.

Messenger RNA (mRNA)

The Pfizer/BioNTech and Moderna vaccines are examples of an mRNA vaccine. This vaccine uses a genetic code, called messenger-RNA (mRNA), to trigger the production of the COVID-19-specific spike protein.

The mRNA from the vaccine enters the cytoplasm of the body’s cells. The cells then use the instructions contained in the mRNA to make the spike protein. Immune cells can then recognise the spike protein as foreign and begin building an immune response against it.

Important: messenger-RNA can’t change or interact with a person’s DNA in any way.

Clinical trials of the Pfizer vaccine, COMIRNATY, show that this vaccine triggers antibodies that can respond to a range of coronavirus mutations. The Australian Government, which has approved this vaccine for people aged 12 and older, will continue to monitor this as more data becomes available.

Protein

The Novavax vaccine is an example of a protein-based vaccine. This uses a non-infectious component of COVID-19, usually the spike protein.

This protein is found on the surface of the virus and can be manufactured in a laboratory. When the vaccine enters the body, immune cells recognise the spike protein as foreign and begin building an immune response against it.

Vector

The AstraZeneca vaccine and Janssen vaccine is an example of a viral vector vaccine. These types of vaccines use a harmless, weakened animal virus that contains the genetic code for a protein unique to COVID-19, usually the spike protein.

This weakened animal virus is known as a ‘viral vector’. Once the viral vector enters the body, immune cells then recognise the spike protein as foreign and begin building an immune response against it.

Do COVID-19 vaccines stop transmission of the virus?

Clinical trials have shown that both the Pfizer and AstraZeneca vaccines protect against COVID-19 symptoms and severe disease after a person receives 2 doses.

It’s not yet known whether these vaccines prevent transmission of the coronavirus (SARS-CoV-2) that causes COVID-19. However, more data is becoming available from vaccination programs in countries like the US and the UK.

One study in the UK has shown that the small number of people who catch COVID-19 despite being vaccinated are less likely to pass the virus on to their household contacts — compared to those who are infected but not vaccinated.

This effectiveness against transmission was seen in half of vaccinated people in the UK from 21 days after the first dose for both the Pfizer and AstraZeneca vaccines.

Can I choose which vaccine I receive?

Many people won’t be able to choose which COVID-19 vaccine they receive.

  • The preferred vaccine for people aged 60 and over is AstraZeneca.
  • The preferred vaccine for people aged 16 to 59 is Pfizer.

However, adults aged 18 to 59 years can receive the AstraZeneca vaccine if they have weighed up the benefits and the risks, and provide informed consent. Talk to your doctor or immunisation provider to help inform your decision.

For more information, see, ‘Can I get the AstraZeneca vaccine?

Are COVID-19 vaccines interchangeable?

The AstraZeneca and Pfizer vaccines are not considered interchangeable. This means that you shouldn’t ‘mix them up’ — your second dose must be the same vaccine as the first to complete the course.

If you develop anaphylaxis or a severe allergic reaction after the first dose of a COVID-19 vaccine, a different type can be considered for the second dose. If an alternative brand is used for the second dose, a third dose of COVID-19 vaccine does not need to be given.

If you develop the rare condition thrombosis with thrombocytopenia (TTS) after the first dose of the AstraZeneca vaccine, the Pfizer vaccine can be used for the second dose. A third dose of COVID-19 vaccine does not need to be given.

How have the COVID-19 vaccines been developed so quickly?

The urgency of the pandemic has meant that all available resources and efforts have been directed towards finding effective vaccines.

Globally, some COVID-19 vaccines were approved and administered just 12 months after the virus was discovered. Usually, development of a vaccine takes several years. Some of the reasons behind this rapid progress include:

  • The levels of funding and collaboration between vaccine developers and governments are greater than ever before. Planning began early, including investment in manufacturing facilities before a vaccine was even available.
  • Technology makes vaccine development faster than in the past. To develop a vaccine, scientists need to understand the virus’s genetic code. New technology allowed researchers to quickly identify the genetic code of the COVID-19 virus soon after it emerged. This allowed scientists around the world to start designing and building vaccines.
  • Clinical trials progress more quickly if a disease is widespread, which is the case for COVID-19 in many countries. This means researchers can evaluate the effect of a vaccine on both unvaccinated and vaccinated groups much sooner than they’d be able with a rare disease.

For more information on the Australian Government’s COVID-19 vaccine strategy, go to health.gov.au and click on ‘COVID-19 vaccines’.


More questions about COVID-19 vaccines

Click on the links below for more questions and answers about COVID-19 vaccines.


Resources in other languages

COVID-19 vaccination resources in other languages are available from the Department of Health.

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Last reviewed: July 2021


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