RESEARCH PAPER SERIES, 2021–22   11 November 2021

COVID-19 vaccines: a quick guide

Emma Vines

Social Policy

Vaccines are central to Australia’s COVID-19 pandemic response. The Australian, state and territory governments have said that a high vaccination rate is crucial to avoiding future widespread lockdowns, with the National Plan to transition Australia’s National COVID-19 Response providing ‘a graduated pathway to transition Australia’s COVID-19 response from its current pre-vaccination settings focused on continued suppression of community transmission, to post-vaccination settings focused on public health management of COVID-19 [that] is consistent with other infectious diseases’.

The reopening of international borders has also been largely based on vaccination rates, with the Therapeutic Goods Administration (TGA) listing ‘recognised vaccines’, which are those used internationally, but not currently registered in Australia. As at 1 November, these vaccines include the Covishield (AstraZeneca/Serum Institute of India), the Coronavac (Sinovac), the Covaxin (Bharat Biotech, India) and BBIBP-CorV (Sinopharm, China) vaccines. Those vaccines whose efficacy is not currently considered to be supported by sufficient evidence, such as the Sputnik V and Convidecia (Cansino) vaccines, have not been designated ‘recognised vaccines’ as at 1 November 2021. One consequence of recognising common vaccines used in countries such as India and China is the reopening of borders to international students—a group specifically identified by the National Cabinet as an important returning cohort once borders reopen.

Australia has entered into several separate agreements for COVID-19 vaccines, investing over $8 billion.

This quick guide provides an overview of COVID-19 vaccines provisionally approved for use in Australia, including the types of vaccines and the approval process. It also briefly considers the COVAX agreement, a program designed to ensure equitable vaccine access worldwide.

This guide does not discuss the rollout of the vaccination program. For information on the number of vaccinations administered in Australia, see the Department of Health’s website.

Given that the pandemic continues to unfold, this guide is up to date as at 11 November 2021. While vaccines often have multiple names and may have changed over time, this guide uses the names most widely recognised in Australia at the time of writing.

Disclaimer: This Quick Guide has been prepared to provide information to support the work of the Australian Parliament. It is for informational purposes only and is not a substitute for independent professional medical advice.

1 (Provisional) approval process for COVID-19 vaccinations

The TGA is responsible for evaluating and regulating therapeutic goods, including vaccines. Given the nature of the pandemic, COVID-19 vaccines have been considered through the provisional approval pathway process, which allows for temporary registration of promising new medicines and vaccines where the need for early access is considered sufficiently important to outweigh the risks.

For a COVID-19 vaccine to be considered for provisional approval, the vaccine must first be considered for provisional determination by the TGA. Table 1 provides a summary of the COVID-19 vaccines that have received a provisional determination. Sponsors then have six months to apply for provisional registration.

Table 1: date of provisional determinations

Effective date

Vaccine

Sponsor

9 October 2020

ChAdOx1-S [recombinant]

AstraZeneca Pty Ltd

14 October 2020

BNT162b2 [mRNA]

Pfizer Australia Pty Ltd

16 November 2020

Ad26.COV2.S

Janssen-Cilag Pty Ltd

19 January 2021

NVX-CoV2373

Biocelect Pty Ltd (on behalf of Novavax Inc.)

24 June 2021

Spikevax (elasomeran)

Moderna Australia Pty Ltd

Source: Therapeutic Goods Administration, ‘COVID-19 vaccine provisional determinations’, Department of Health, 24 June 2021.

To apply for provisional approval of its vaccine, the sponsor must submit an application that includes information on ‘clinical studies, non-clinical/toxicology studies, chemistry, manufacturing, risk management and other information’. Table 2 shows the dates of provisional registrations granted to COVID-19 vaccines.

Table 2: date of provisional registrations and amendments to approved age cohorts

Effective date

Sponsor and vaccine

Age modifications

25 January 2021

Pfizer Australia Pty Ltd (BNT162b2)

22 July 2021: provisionally approved for individuals aged
12–15 years

27 October 2021: provisionally approved for a third dose for individuals aged 18 years and over and for severely immunocompromised individuals aged 12 years and over

15 February 2021

AstraZeneca Pty Ltd (ChAdOx1-S)

8 April 2021: Pfizer recommended as preferred vaccine for those aged under 50 years

17 June 2021: Pfizer recommended as preferred vaccine for those aged 16–60 years

25 June 2021

Janssen-Cilag Pty Ltd(Ad26.COV2.S)

Approved for those 18 years and over

9 August 2021

Moderna Australia Pty Ltd (Spikevax (elasomeran))

3 September 2021: provisionally approved for individuals aged
12–17 years

10 November 2021: granted provisional determination to apply to vary the provisional approval in relation to administering the vaccine to children aged 6 to 11 years.

Source: Therapeutic Goods Administration, ‘COVID-19 vaccine: Provisional registrations’, Department of Health, 27 October 2021.

The decision to approve or reject an application is ‘always made by the TGA on the basis that the benefits outweigh the risks’ and the decision is based on factors such as:

the safety, quality and effectiveness of the vaccine has been satisfactorily established for its intended use

the sponsor's plan to submit comprehensive clinical data, stability data and other information before the provisional registration ends.

Once approved, a vaccine is included in the Australian Register of Therapeutic Goods (ARTG) and, under provisional registration, may be lawfully supplied in Australia by the sponsor for a period of two years, with the possibility of up to two extensions to a maximum of six years overall.

2 Vaccine agreements

Agreements are in place for the vaccines approved for use in Australia, shown in Table 3. Of the five, one was cancelled, with the University of Queensland vaccine not proceeding past Phase 1 trials and consequently not receiving provisional approval.

Secretary of the Department of Health, Brendan Murphy, has explained the Government’s initial decisions in relation to these agreements as follows:

… at the time when we made the strategic investment in Pfizer none of the vaccines had proven phase 3 clinical trial data and no mRNA vaccine had ever been used in humans. So our scientific and technical advisory group [Science and Industry Technical Advisory Group (SITAG)] had a strong preference for protein subunit vaccines, which is why we did University of Queensland and Novavax—50,000-plus of each—and then a strategic purchase with local production of an adenovirus vaccine, AstraZeneca, which was the next most proven technology, and a strategic investment in the as yet unproven Pfizer on the 10 million they offered us, with an option to increase should it be successful and should we have issues with other vaccines. All of those options have been exercised.

In relation to the decision to initially invest in Pfizer, rather than Moderna, Mr Murphy previously said that SITAG ‘wanted to make a recommendation of an investment of one of the MRNA [sic] vaccines and, for a variety of reasons, we recommended Pfizer. They're both very similar vaccines with very similar efficacy; there is not much difference between them in the published data’. The Government has since announced an agreement to provide the Moderna COVID-19 vaccine.

Table 3: vaccine agreements   

Date agreement was announced

Doses secured or optioned (million)

Vaccine

Vaccine developer/ manufacturer

Type of vaccine

7 September 2020

33.8

Vaxzevria

AstraZeneca / CSL

Viral vector

11 December 2020

20.0

7 September 2020

51.0*

University of Queensland

University of Queensland / CSL

Protein subunit

5 November 2020

40.0

NVXCoV-2373

Novavax / Novavax

Protein subunit

11 December 2020

11.0

5 November 2020

10.0

Comirnaty

Pfizer BioNTech / Pfizer BioNTech

mRNA

4 February 2020

10.0

9 April 2021

20.0

25 July 2021

85.0**

15 August 2021

1.0***

3 September 2021

4.0****

13 May 2021

25.0

mRNA-1273

Moderna / Moderna

mRNA

Source: Department of Health, ‘Australia’s vaccine agreements’, Australian Government, 2 September 2021.

* Cancelled

** Extra doses secured for booster vaccines to be provided in 2022–23

*** Extra doses secured from Poland

**** Extra doses secured through a dose sharing partnership with the United Kingdom

3 Types of vaccines approved for use in Australia

Currently, the COVID-19 vaccine types in use in Australia are messenger RNA (mRNA) vaccines (Pfizer/BioNTech Comirnaty and Spikevax (Moderna)) and a viral vector vaccine (AstraZeneca (now known as Vaxzevria)).

Australia also has an agreement for the Novavax vaccine, which is a protein subunit vaccine currently undergoing evaluation by the TGA. Although not currently in use in Australia, an explanation of this type of vaccine is included below.

The cancelled UQ-CSL v451 COVID-19 vaccine, developed by the University of Queensland and Australian biotechnology company CSL Limited, was also a protein subunit vaccine. This vaccine did not proceed past Phase 1 trials as it generated antibodies that led to ‘false-positive’ HIV test results.

In mid-September 2021 the Australian Technical Advisory Group on Immunisation (ATAGI) recommended focusing on maximising COVID-19 vaccine supply for first and second doses for the community. On 7 October, ATAGI provided updated advice, recommending a third primary dose for people who are severely immunocompromised. In conjunction with the TGA’s provisional approval on 27 October to use the Pfizer vaccine for booster doses, ATAGI recommended booster doses of the COVID-19 vaccine for the general population, noting, however, that the first priority should continue to be very high vaccination rates of two doses for all eligible people in Australia. As part of this recent recommendation, ATAGI indicated that people with risk factors for severe COVID-19 and/or those at occupational risk of COVID-19 should be prioritised for the initial booster doses. On 28 October, the Prime Minister announced COVID-19 vaccine boosters would be available for eligible people from 8 November 2021.

mRNA vaccines

mRNA vaccines contain pieces of genetic material that enable a person’s cells to start making a viral antigen. In the case of some COVID-19 vaccines, this is to make a spike protein (S protein). S proteins are found on the surface of the SARS-CoV-2 virus (the virus that causes COVID-19) and assist the virus to enter a human cell. Following a vaccination, the body starts making copies of the S protein, which the immune system recognises as foreign and against which it produces long-lasting immune cells and antibodies. The intended result is that when a person is later exposed to the SARS-CoV-2 virus, the immune system is better prepared to fight it.

One of the initial challenges with using mRNA vaccines was the storage requirements, with the Pfizer vaccine requiring storage at -70 °C. However, the advice regarding short-term storage has changed over time with advice in May 2021 approving Pfizer’s application to allow unopened, thawed vials to be kept in a fridge (2–8 °C) for up to one month instead of five days.

Based on current advice, both Pfizer and Moderna require two doses of the vaccine to be fully effective. Pfizer requires a minimum of 21 days between the first two doses, while Moderna requires the two doses to be 28 days apart. A third Pfizer dose has been provisionally approved for use at six months after the second dose to extend the vaccine’s effectiveness.

Based on advice current at 13 September 2021, both Pfizer and Moderna have been approved by the TGA for use in those aged 12 years and over.

Viral vector vaccines

The AstraZeneca vaccine is a viral vector vaccine. This type of vaccine uses a different modified virus (the vector) to deliver genetic instructions to the body’s cells to start making the SARS-CoV-2 S protein. This then triggers an immune response producing antibodies and immune cells.

While AstraZeneca is the only viral vector vaccine currently used in Australia’s vaccination program, a second viral vector vaccine is also provisionally approved for use: the Janssen or Johnson & Johnson, vaccine. This vaccine has been used overseas and requires only a single dose. On 13 April 2021, the Minister for Health, Greg Hunt, stated that the Government had not been advised to purchase additional viral vector vaccines.

AstraZeneca requires two doses. Initially it was advised that the doses should be 12 weeks apart, but, given the escalating Delta variant outbreak, some jurisdictions brought this forward to between four and 12 weeks, based on updated advice.

Advice regarding AstraZeneca and its use in various age groups has changed over time. Although it is approved for those aged 18 and over, Pfizer and Moderna are currently preferred for those under the age of 60. However, in July 2021 ATAGI recommended that individuals younger than 60 in outbreak areas who do not have access to Pfizer, ‘re-assess the benefits to them and their contacts from being vaccinated with COVID-19 Vaccine AstraZeneca, versus the rare risk of a serious side effect’.

Protein subunit vaccines

Protein subunit vaccines introduce purified pieces of the COVID-19 S protein. The Novavax vaccine uses laboratory-made spike proteins, assembled into nanoparticles which resemble the structure of SARS-CoV-2 virus. They do not contain any live components of the virus. Adjuvants (molecules which boost a person’s immune system) increase the immune response, encouraging protective immunity.

While Novavax is not currently approved for use in Australia as at 27 October 2021, it is undergoing evaluation by the TGA. It is expected that should Novavax be provisionally approved for use, it will require two doses.

4 Efficacy of vaccines approved for use in Australia

The TGA has reviewed the efficacy of vaccines approved for use in Australia and those used overseas and recognised by Australia.

The efficacy of each vaccine approved for use in Australia against specific outcomes as assessed by the TGA is shown in Table 4.

Table 4: Efficacy of vaccines in preventing infection and hospitalisation

Vaccine

Outcome prevented

Average vaccine efficacy

AstraZeneca (Vaxzevria)

Symptomatic infection

65%

Severe infection / hospitalisation

85%

Pfizer (Comirnaty)

Symptomatic infection

81%

Severe infection / hospitalisation

88%

Moderna (Spikevax)

Symptomatic infection

86%

Severe infection / hospitalisation

81%

Janssen (COVID-19 Vaccine Janssen)

Symptomatic infection

66%

Severe infection / hospitalisation

85%

Source: Therapeutic Goods Administration, ‘COVID-19 vaccines not registered in Australia but in current international use—TGA advice on “recognition”’, Department of Health, 1 October 2021.

5 Adverse events

The TGA continues to monitor approved vaccines and publishes weekly safety reports that contain information about reported adverse events.

Anyone can report an adverse event by phone, email or online. Reported adverse events are then searchable through the Database of Adverse Event Notifications (DAEN). There are separate databases for medicines and medical devices. The DAEN is searchable by medicine and includes information on the organ class affected (for example, nervous system disorder); the reaction (for example, headache or lethargy); the number of cases reported; the number of cases with a single suspected medicine involved; and the number of cases where a death was reported.

The TGA makes clear that these reports do not necessarily mean the specific medication or vaccine necessarily caused the adverse event. The most publicised adverse events have been those related to the AstraZeneca vaccine, which has been connected to a rare and serious condition known as thrombosis with thrombocytopenia syndrome (TTS) (blood clots with low platelet levels). The majority of TTS cases have occurred following the first dose of the vaccine and the onset of symptoms is generally between four and 30 days after vaccination and more common among those aged under 60 years.

As at 5 November 2021, the risk of TTS is estimated in Australia following this vaccine is around:

• 2.5 per 100,000 people aged less than 60 years

• 1.8 per 100,000 people aged 60 years and over.

TTS has also been reported following vaccination with the Johnson & Johnson COVID-19 vaccine.

6 COVAX

In September 2020, Australia joined the COVAX Facility, which aims to ‘accelerate the development and manufacture of COVID-19 vaccines, and to guarantee fair and equitable access for every country in the world’. It is jointly led by Gavi, the Coalition for Epidemic Preparedness Innovations, UNICEF and the World Health Organization. COVAX involves over 90 ‘upper-income countries’, including Australia, and 92 ‘lower-income countries’ and originally aimed to mobilise two billion doses by the end of 2021. However, revised estimates are that 1.4 billion doses will have been made available by the end of 2021, with a total of 2.6 billion doses forecast to have been made available by the end of March 2022.

Australia has made three financial commitments to the COVAX Facility, including two investments to the Advanced Market Commitment (AMC) of the COVAX Facility. These include an investment in August 2020 of $80 million and a further $50 million to the AMC in June 2021. This money is intended ‘to improve access for Pacific and Southeast Asian countries to safe, effective and affordable COVID-19 vaccines’.

Australia also has an agreement to secure ‘up to 50 per cent [Australian] population coverage through COVAX’. In June 2021, Minister Hunt announced that 500,000 Pfizer doses had been secured through COVAX as part of the Australian Government’s $123.2 million purchase made through the program in September 2020.

However, the distribution of doses to upper-income countries including Australia has been questioned by groups such as the Australian Council for International Development and a report co-authored by an Expert Advisory Group formed by members of humanitarian organisations has called on the Australian Government to make further financial commitments to COVAX.

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