Third dose for severely immunocompromised people – COVID-19 vaccine

Third doses are for eligible severely immunocompromised people as part of a 3-dose primary course. Third doses are not a booster dose. Additional booster doses may be required for people eligible for a third dose.

Severely immunocompromised people aged 5 and over are strongly encouraged to receive a third dose of the COVID-19 vaccine 2–6 months after the second dose.

This is because you may have a decreased immune response to the standard 2-dose COVID-19 vaccination schedule and be more at risk from severe COVID-19. This third dose is to maximise your level of immune response to as close as possible to the general population.


  • Over 12 years of age with severe immunocompromise—refer to the ATAGI statement for a list of included medical conditions.
  • 2–6 months since your second COVID-19 vaccine dose

People who are mildly to moderately immunocompromised are not recommended by ATAGI to have a third dose at this stage.

How to book

Speak with your GP or treating specialist to discuss your individual circumstances. You can book a third dose appointment online or with a participating GP or pharmacy. You may be asked to provide evidence of your medical condition or a referral letter from your GP or specialist at your appointment.

Find a clinic and book

Find a walk-in vaccination clinic

Vaccine types for third doses

The Pfizer (Comirnaty) or Moderna (Spikevax) vaccines are the recommended third dose regardless of which vaccine you had for your first 2 doses.

You can also receive the AstraZeneca (Vaxzevria) vaccine if you:

  • can’t have the Pfizer or Moderna vaccine for medical reasons
  • had 2 doses of the AstraZeneca vaccine previously.

Vaccination records and certificates

Details of your third dose will automatically be uploaded to your Immunisation History Statement and your COVID-19 vaccination certificate will be updated to show your last 2 doses.

Read more about getting proof of your COVID-19 vaccination.