The Australian Technical Advisory Group on Immunisation (ATAGI) has recommended a third dose of Covid-19 vaccine as part of the primary course in individuals who are severely immunocompromised.
An mRNA vaccine (Pfizer or Moderna) is preferred to Vaxzevria (AstraZeneca) for this third dose. However, AstraZeneca can be used for the third dose for individuals who have received AstraZeneca for their first two doses.
The recommended interval for the third dose is two to six months after the second dose of vaccine. A minimum interval of four weeks may be considered in exceptional circumstances (e.g., anticipated intensification of immunosuppression, outbreaks). People who have had a second dose more than six months ago should receive a third dose whenever feasible.
ATAGI says it will continue to monitor the evidence around duration of protection and advise on the need for subsequent (booster) doses in immunocompromised populations to address waning of protection or risk from variants of concern.
For the general population, ATAGI will provide further advice on booster doses, including for healthcare workers and older adults separately.