Immunocompromised vaccination explained

With the rollout of a fourth COVID shot for older West Australians and those at risk, people who are severely immunocompromised will also be eligible for what may be their fifth inoculation.


People aged 16 years and older who received a three-dose primary series, and a booster (fourth) dose are now recommended to receive a fifth additional winter shot, four months after their first booster.

People with immunocompromising conditions (or therapies) are at increased risk of severe outcomes due to COVID, with studies showing that the immunocompromised population have a 1.5 to two times higher risk of death from COVID than the general population.

In addition, immunocompromised individuals can have prolonged COVID infection and viral shedding, which can increase the risk of viral evolution during infection and breakthrough infections as well as the development of new viral variants.

They also had a risk of poor to no response to the standard two dose schedule which most Australians received.

To address these issues, a third primary dose of COVID vaccine in severely immunocompromised people was recommended by ATAGI, in consultation with the Australasian Society of Clinical Immunology and Allergy (ASCIA).

The third dose was intended to maximise the level of immune response to as close as possible to the general population and ATAGI also recommended that individuals aged five years and over, with certain conditions or on therapies leading to severe immunocompromise, received a third primary dose of vaccine.

The recommended interval for the third dose was two months after the second dose of vaccine, though in exceptional circumstances a minimum interval of four weeks was considered possible.

This differed from the timing of the third shot (or first booster) for the general population, which was three months after their second dose.

ATAGI recommended using an mRNA-based vaccine (Pfizer or Moderna) or if necessary, Novavax, though people who received the first and second doses of AstraZeneca were able to use it for their third dose, provided there were no contraindications or precautions since their last shot.

This was largely because most studies supporting a third dose of COVID vaccine in immunocompromised people used mRNA vaccines for the whole series, and there are currently no studies in immunocompromised populations to directly inform the use of a third shot after two doses of AstraZeneca or Novavax.

Immunocompromised people received their first booster (fourth) dose from three months after completing the three primary doses which is why, some four months later, they are now eligible for what may be their fifth dose.

As there are no studies to date on the use of a fifth dose of vaccine in this population, ATAGI recommends the additional booster dose for these people based on first principle and will continue to monitor immunocompromised populations to address waning protection or risk from variants of concern.

ATAGI also states that, “protection from three primary doses in severely immunocompromised individuals, with or without a booster or winter dose, may still be lower than the general population and strategies such as mask wearing and social distancing should continue to be used, even after further doses.”

Those interested in finding out more can visit https://www.health.gov.au/news/atagi-statement-on-recommendations-on-a-winter-booster-dose-of-covid-19-vaccine