This is what ATAGI recommends:
“A third primary dose of COVID-19 vaccine is recommended for people aged 5 years or older with severe immunocompromise from 2 months after the second vaccine dose.
This dose is intended to address the risk of lowered or non-response to the standard 2 dose schedule.
An mRNA COVID-19 vaccine (Pfizer or Moderna) is recommended for the third dose. This is because most studies of third doses of COVID-19 vaccine in immunocompromised people have used mRNA vaccines.
The Novavax COVID-19 vaccine can be used for the third dose for people who have received Novavax for their first 2 doses, or if there are contraindications to mRNA COVID-19 vaccines. There is very limited evidence of the efficacy of Novavax in immunocompromised people.
The AstraZeneca COVID-19 vaccine is not preferred but can be used for the third dose if there are contraindications to mRNA COVID-19 vaccines.
Severely immunocompromised people aged 16 years or older who have received a third primary dose are recommended to receive a booster dose (a fourth dose), 3 months after the primary course, in line with the general population.
More information, including definitions of severe immunocompromise, is available in ATAGI recommendations for the use of a 3rd primary dose of COVID-19 vaccine in individuals who are severely immunocompromised.
There are many causes and varying degrees of immunocompromise. The risk of COVID-19 will vary according to:
- the number and type of underlying conditions
- medical management
- other factors.”
For more information, visit the Australian Technical Advisory Group on Immunisation (ATAGI) clinical recommendations for COVID-19 vaccines.
What is happening internationally?
Earlier this year, Israel began offering a fourth dose of the Pfizer mRNA vaccine to people who are immunocompromised, older people, and frontline health workers. Israeli medical experts have since suggested fourth doses for everyone over 18.
Preliminary data from Israel suggests a fourth dose for people over 60 offers up to two times more protection against infection, and three times more against severe disease compared to those who have received a third dose at least fourth months prior.
The UK, Denmark, Belgium, Italy, Chile and Sweden are some of the countries that have approved a fourth dose for immunocompromised people.