How COVID-19 vaccines are tested and approved

Australia has strict requirements for the testing and approval of vaccines. Learn how clinical trials work, and how vaccines get approved for use.

How COVID-19 vaccines are being tested

Before a vaccine is registered for use, it is tested extensively during development and then in thousands of people. Testing first 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.

Phase 1

Phase 1 clinical trials usually include a few dozen healthy adult volunteers. They focus primarily on establishing that the vaccine is safe, and also on demonstrating that the vaccine induces an immune response.


Phase 2

Phase 2 clinical trials have hundreds of volunteers, and can include specific groups for whom the new vaccine is intended. For example older adults, children or people with pre-existing medical conditions. These trials aim to test whether the vaccine causes an immune response and confirm that it is safe with minor side effects, such as a mild headache.


Phase 3

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.

In a Phase 3 trial, researchers usually compare data between vaccinated people and those who received a placebo (like a salt water injection). 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. Some Phase 3 studies have started once preliminary data from phase 1and 2 trials are available. Having these ‘overlapping’ time frames has helped develop COVID-19 vaccines quickly, to make them available earlier to save lives.

How a vaccine is approved for use in Australia

Before a COVID-19 vaccine is approved for use in Australia, it must pass the Therapeutic Goods Administration’s (TGA) 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.  

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