COVID-19 vaccine safety, testing and trials


Following a review of the use of the COVID-19 AstraZeneca vaccine, the Australian Technical Advisory Group on Immunisation (ATAGI) recommends that the COVID-19 vaccine by Pfizer is preferred over the COVID-19 vaccine by AstraZeneca in adults aged under 50 years. Find out more.

How is a vaccine approved for use in Australia?

The COVID-19 vaccines being used in Australia have been approved by the Australian Government’s Therapeutic Goods Administration (TGA) and administered under the advice of the COVID-19 Vaccine and Treatments for Australia – Science and Industry Technical Advisory Group and the Australian Technical Advisory Group on Immunisation (ATAGI).

Before any vaccine is registered for use, it is tested extensively during development and then in thousands of people. Testing begins with laboratory research, then animal studies and finally human clinical trials. Clinical trials involve testing the vaccine in volunteers, and are conducted in phases.

Before any vaccine is approved for use in Australia, including a COVID-19 vaccine, it must pass the TGA’s rigorous assessment and approval processes. This includes assessment of its safety, quality and effectiveness.

The TGA is actively monitoring COVID-19 vaccine development both in Australia and around the world, and is also part of a network of international regulators that meet regularly to discuss the development of COVID-19 vaccines.

The TGA is engaging early with vaccine developers, undertaking a thorough and efficient review of vaccine candidates and discussing the application process. Early engagement will not affect the comprehensive review process that clinical trial results are subject to in Australia.

Are the COVID-19 vaccines safe?

The COVID-19 vaccines are thoroughly tested for safety before they are approved for use in Australia. This includes careful analysis of clinical trial data, ingredients, chemistry, manufacturing and other factors.

The Therapeutic Goods Administration (TGA) approves all COVID-19 vaccines being used in Australia to ensure that extremely high safety standards are met. The vaccines available do not use the live or whole virus that causes COVID-19.

With hundreds of millions of people vaccinated globally with these vaccines, real world data is now showing high effectiveness for both vaccines.

Real-world data has also uncovered an extremely rare blood clotting syndrome, which may be linked to the AstraZeneca vaccine. The TGA and the Australian Technical Advisory Group on Immunisation (ATAGI) responded quickly to this real-world data, updating their advice to provide new guidelines for the use of AstraZeneca in Australia.

We can be confident that both vaccines are safe and provide protection against serious illness and death from COVID-19.

Is anybody monitoring the safety of the vaccines in Australia?

In addition to providing approval for the COVID-19 vaccines to be used in Australia, the Therapeutic Goods Association (TGA) tests every batch of COVID-19 vaccines – checking how potent they are ensuring they have not been contaminated – before they are dispatched for delivery.

Vaccine recipients may also be followed up with an automated text message three days and then eight days after your vaccination. You may be asked if you have had any side effects, and the information will contribute to AusVaxSafety’s national COVID-19 vaccine safety surveillance.

AusVaxSafety is a world-leading national vaccine safety system, led by the National Centre for Immunisation Research and Surveillance.

The TGA and the Australian Technical Advisory Group on Immunisation (ATAGI) are both monitoring the safety of the vaccines in Australia and overseas, and have already updated their advice to ensure the safety of all Australians.

How were the COVID-19 vaccines developed and approved in a short timeframe?

All available resources and efforts have been directed towards finding an effective vaccine, due to the urgency of protecting people from the COVID-19 virus.

Some of the reasons behind this rapid progress include:

  • Unprecedented levels of funding and collaboration between vaccine developers and governments around the world. Planning has been undertaken early, such as investing in manufacturing facilities before a vaccine is even available.
  • Technology has evolved to make vaccine development faster than in the past. To develop a vaccine, scientists need to understand the virus’s genetic code. New technology has allowed researchers to quickly identify the genetic code of the COVID-19 virus, soon after the virus emerged. This allowed scientists around the world to start work in designing and building vaccines.
  • Clinical trials progress more quickly if a disease is widespread, which is the case for COVID-19. This means researchers can evaluate the effect of a vaccine between the unvaccinated and vaccinated groups much sooner than for a rare disease.

Why were the COVID-19 vaccines available earlier overseas?

Some countries have used emergency use authorisation to roll the COVID-19 vaccine out more quickly. Emergency use authorisation is not a full approval of a vaccine. In countries facing significant COVID-19 outbreaks, the benefits of rolling out a vaccine before full regulatory assessment may outweigh the risk of waiting for a full analysis.

Due to the proactive management of COVID-19 in Australia, we have been able to wait for the Therapeutic Goods Administration (TGA) to make an assessment through the provisional registration pathway. This allows the TGA to undertake its comprehensive regulatory assessment of the safety and effectiveness of vaccine candidates.

What was involved in COVID-19 vaccine trials?

Before any vaccine is registered for use, it is tested extensively during development and then in thousands of people. Testing begins with laboratory research, then animal studies and finally human clinical trials. Clinical trials involve testing the vaccine in volunteers, and are conducted in phases.

Clinical trials must provide scientific evidence which demonstrates that the benefits of a vaccine greatly outweigh any risks.

There are different types of clinical trials:

  • Phase 1 clinical trials usually include a few dozen healthy adult volunteers. They focus primarily on establishing that the vaccine is safe, and on demonstrating that the vaccine induces an immune response.
  • Phase 2 clinical trials have hundreds of volunteers, and can include specific groups the vaccine is intended for. These trials aim to test whether the vaccine causes an immune response and confirm that it is safe with minor side effects.
  • Phase 3 clinical trials include many thousands of participants. They aim to test whether a vaccine is effective in preventing people from getting the disease – in this case COVID-19. Phase 3 trials also thoroughly assess the vaccine for safety and side effects. Researchers usually compare data between vaccinated people and those who received a placebo. They compare the frequency of infection, disease severity and any reported side effects between the two groups.

For COVID-19 vaccines, some of these phases have been combined. For example, in Phase 1 and 2 trials, results are analysed after the first few dozen volunteers are studied. The trial then proceeds in hundreds more people. Some Phase 3 studies have started once preliminary data from Phase 1 and 2 trials are available. Having these ‘overlapping’ timeframes has helped develop COVID-19 vaccines quickly, to make them available earlier to save lives.

Does priority access to the vaccine also mean that it is being trialled on me?

No. The vaccines have been through clinical trials and have been approved by the Therapeutic Goods Administration (TGA) for use in Australia through a rigorous assessment and approval processes. This includes assessment of their safety, quality and effectiveness.

Hundreds of millions of people across the world have now received at least one dose of a COVID-19 vaccine.

What checks are in place to ensure people receive the correct dosage of the COVID-19 vaccine?

The person vaccinating you will have completed COVID-19 vaccination training. In South Australia, two trained staff members check the dosage prior to vaccination as an additional safety measure.

The Australian Government partnered with the Australian College of Nursing to develop and deliver the accredited training modules. This will ensure vaccinators can safely manage and administer COVID-19 vaccines.