COVID-19 vaccines: third doses and booster doses

The Australian Technical Advisory Group on Immunisation (ATAGI) now recommend a third dose of a COVID-19 vaccine or a booster dose for individuals who meet certain criteria.

It’s important to know that third doses and boosters are different, and the eligibility criteria for each also differ.

What’s the difference between a third dose and a booster dose?

Third doses

Third doses are for severely immunocompromised people as an additional dose to their 2 dose primary course.

It is for people where 2 doses are not as effective.

The third dose aims to maximise the level of immune response to as close as possible to the general population.

A third dose is recommended 2 to 6 months after the second dose.

A minimum interval of 4 weeks may be considered in exceptional circumstances.

A third dose is not classified as a booster.

If you are severely immunocompromised, talk to your healthcare provider about whether a third dose is right for you.

Booster doses

ATAGI anticipates that booster doses of COVID-19 vaccines are likely to be needed, in time, for all people aged 18 years and over.

Booster doses work to keep you protected against COVID-19 as your immunity reduces or as new variants emerge.

ATAGI recommends a single booster dose for those who completed their primary COVID-19 vaccine course at least 6 months ago.

In severely immunocompromised individuals who have recently received a third dose of a primary COVID-19 vaccine, a booster (fourth) dose is not yet recommended.

COVID-19 vaccine third doses for severely immunocompromised individuals

ATAGI recommends a third dose of COVID-19 vaccine as part of the primary course in individuals who are severely immunocompromised.

This is a third dose to complete the regular course of vaccination for a very specific group of vulnerable people.

A third dose aims to maximise the level of immune response and make sure these individuals have the highest level of protection against COVID-19.

Third dose eligibility criteria information is available from the Australian Government Department of Health website.

If you are severely immunocompromised you should reach out to your GP or treating specialist to discuss your individual circumstances.

An mRNA vaccine (Pfizer or Moderna) is preferred for third dose vaccinations.

If you are eligible for a third dose (individuals who are severely immunocompromised), you can get it at:

How to book your third dose at an ACT Government clinic

If you are eligible for a third dose, complete the Commonwealth Eligibility Self Declaration Form and provide evidence of eligibility, such as a referral letter from your treating physician.

You can book your third dose appointment over the phone by calling the ACT COVID-19 booking line on, 02 5124 7700, 7am to 7pm, daily.

COVID-19 vaccine booster doses for the general population

If you’ve had 2 doses of COVID-19 vaccine, a booster dose will provide you with even more protection against falling seriously ill from COVID-19.

A booster dose may also reduce the potential of infected individuals to transmit the virus to others.

ATAGI has recommended the Pfizer (Comirnaty) COVID-19 vaccine as the approved vaccine for COVID-19 booster vaccinations.

ATAGI also advises that people most likely to benefit from a booster dose are those with risk factors for severe COVID-19 and those at increased occupational risk of COVID-19.

This includes people:

  • aged 50 years and older
  • those with underlying medical conditions
  • residents of aged care and disability facilities, and
  • Aboriginal and Torres Strait Islander people aged 18 years and over.

Who can get a COVID-19 vaccine booster dose?

You can get a COVID-19 vaccine booster dose if:

  • you are aged 18 years and over
  • you’ve had 2 doses of COVID-19 vaccine, and
  • your second dose of COVID-19 vaccine was at least 6 months ago.

If this applies to you, you can get a Pfizer booster now.

This includes people who received another COVID-19 vaccine brand (AstraZeneca or Moderna) for their first 2 doses.

Booster vaccinations are not recommended if you:

  • are aged under 18 years of age
  • have already received a third dose as an individual who is severely immunocompromised
  • received your second dose of COVID-19 vaccine less than 6 months ago.

If you are unsure about getting a COVID-19 booster vaccination, speak to your GP or another trusted health care professional to help you make an informed decision.

Booking a booster vaccination appointment

You can get a booster dose at:

How to book your booster dose at an ACT Government clinic

ACT Government COVID-19 vaccination clinics are accepting booster vaccination bookings for people who had their second dose of COVID-19 vaccine before the end of June 2021.

These clinics offer the Pfizer COVID-19 vaccine only.

Anyone who is eligible can make an appointment for a booster vaccination at an ACT Government clinic by:

  • calling the ACT COVID-19 vaccination booking line on 02 5124 7700, 7am to 7pm, daily
  • booking online using MyDHR.if you had your second dose appointment at an ACT Government clinic.

If you had your second dose of COVID-19 vaccine at an ACT Government clinic, you will be contacted by ACT Health when you become eligible to book in for your booster dose.

We will provide further information when bookings at ACT Government COVID-19 vaccination clinics open for people who received their second dose of COVID-19 vaccine after the end of June.

Frequently Asked Questions

Third doses

Who can get a third dose of a COVID-19 vaccine?

People aged 12 years and over who are severely immunocompromised are recommended a third dose of a COVID-19 vaccine.

If you are severely immunocompromised you should reach out to your GP or treating specialist to discuss your individual circumstances.

How long after my second dose should I get a third dose?

It is recommended that people who are severely immunocompromised receive a COVID-19 vaccine 2 to 6 months after the second dose of the COVID-19 vaccine.

A minimum interval of 4 weeks may be considered in exceptional circumstances.

Which vaccine should I get as my third dose?

An mRNA vaccine (Pfizer or Moderna) is preferred for third dose vaccinations.

If you had a significant adverse reaction after a previous mRNA vaccine dose (Pfizer or Moderna), like anaphylaxis or myocarditis, you should speak to your GP or treating health professional about getting a third primary dose of the AstraZeneca (Vaxzevria) vaccine.

Speak to your GP or treating specialist about whether a COVID-19 booster vaccination is right for you.

Do I have to get a third dose?

Third doses aren’t mandatory.

However, they are recommended for people who are severely immunocompromised to ensure you maximise your protection as close as possible to the general population.

If you are severely immunocompromised you should reach out to your GP or treating specialist to discuss your individual circumstances and whether a third dose is right for you.

Will my third dose be recorded in the Australian Immunisation Register? 

The clinic where you receive your third dose will record it in the Australian Immunisation Register (AIR).

It’s important to know that you’re considered fully vaccinated once you’ve received 2 doses of COVID-19 vaccine.

This means your vaccination status doesn’t change in the AIR once you’ve had a third dose of COVID-19 vaccine.

Booster doses

Do I have to get a booster dose?

Booster doses aren’t mandatory.

However, they are recommended to ensure you maximise your protection against becoming severely unwell from COVID-19.

If you are unsure about getting a booster dose, speak to your GP or another trusted health care professional to make an informed decision for your health.

What are the benefits of getting a COVID-19 booster dose?

Booster doses are anticipated to increase protection from severe disease, particularly in older people.

A booster dose may also reduce the potential of infected individuals to transmit the virus to others.

Can I get a booster dose that isn’t the Pfizer vaccine?

If you had a significant adverse reaction after a previous mRNA vaccine dose (Pfizer or Moderna), like anaphylaxis or myocarditis, you should speak to your GP or treating health professional about getting a third primary dose of the AstraZeneca (Vaxzevria) vaccine.

How long after my booster vaccination will I need to get another COVID-19 vaccination?

This is not yet known.

ATAGI will provide advice on this in due course.

Will my booster dose be recorded in the Australian Immunisation Register?

The clinic where you receive your COVID-19 booster dose will record it in the Australian Immunisation Register (AIR).

It’s important to know that you’re considered fully vaccinated once you’ve received 2 doses of COVID-19 vaccine.

This means your vaccination status doesn’t change in the AIR once you’ve had a booster dose.

It hasn’t yet been 6 months since my second dose of COVID-19. Can I book a booster earlier?

Booster doses are only people who received their second dose of COVID-19 more than 6 months ago.

You can book your booster dose at a Government clinic if you had your second dose before the end of June.

There will be further announcements about when bookings at ACT Government clinics will open for those people who were fully vaccinated after the end of June.

If I have a booster vaccination, can I still get COVID-19?

If you’re fully vaccinated against COVID-19 there’s still a possibility that you could contract or transmit the virus to others.

While the booster dose can maximise protection against becoming severely unwell from COVID-19, it’s still important to continue taking COVID-19 safe behaviours, even after you’ve been vaccinated.

This will also help to reduce the likelihood of transmission of COVID-19 to others.

Can I get my COVID-19 booster vaccine and other types of vaccines, like the flu vaccine, at the same time?

ATAGI recommends that it is acceptable to co-administer a COVID-19 booster vaccine dose with an influenza (flu) vaccine.

Data on the potential for co-administration with other vaccines is currently being reviewed.

Detailed information on this will be included in the upcoming revised ATAGI Clinical Guidance on Use of COVID-19 Vaccine in Australia.

More information:

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Acknowledgement of Country

We acknowledge the Traditional Custodians of the ACT, the Ngunnawal people. We acknowledge and respect their continuing culture and the contribution they make to the life of this city and this region.

Last Updated: November 13 2021