Some groups of people will be able to receive their fourth — and in some cases, their fifth — dose of a COVID-19 vaccination.

Here’s what you need to know about the “winter booster” program.

Who can get a fourth COVID jab?

The Australian Technical Advisory Group on Immunisation (ATAGI) has recommended an additional vaccine dose for the following groups:

• Anyone aged 65 years and older
• People who live in aged care or disability care facilities
• People aged 16 and over who have been deemed severely immunocompromised
• Aboriginal and Torres Strait Islander people aged 50 years and older

ATAGI says people in these categories are at the greatest risk of severe illness from COVID-19.

In the case of some severely immunocompromised people who received three doses as part of their primary vaccination series, followed by a booster, this program means they are now eligible for their fifth shot.

How long do I need to wait after my last dose?

Four months.

But if you’ve had COVID-19 since receiving your booster shot, you have to wait until four months after you acquired the infection.

People may be able to receive the vaccine after a shorter interval in special circumstances, but that wait time cannot be less than three months.

Which vaccine should I get for my fourth shot?

Pfizer and Moderna — both of which as mRNA vaccines — are ATAGI’s preferred vaccines.

But the AstraZeneca vaccine can be used when someone can’t have an mRNA vaccine for medical reasons or if they decline one.

Novavax is also approved to be administered as a fourth dose, but only if no other vaccine is considered suitable for that person.

Do I need to get a fourth dose to be considered up to date?

That depends.

The federal government says you must have had “all doses recommended for your age and health needs” to be considered up to date with your COVID-19 vaccination.

People who are considered severely immunocompromised are recommended to have an additional booster, however, because the Australian Immunisation Register doesn’t contain any information on medical conditions, only a total of three doses will be counted as being up-to-date in this sub-group.

Can I get my flu vaccine at the same time as my fourth dose?

Yes.

The “winter booster” program is being rolled out with this year’s influenza vaccination program and ATAGI says both can be administered at the same time.

But if you’re not yet eligible for a fourth COVID, a flu vaccine can be administered earlier.

Why aren’t fourth doses recommended for everyone?

At the moment, ATAGI says there’s “insufficient evidence of the benefits of an additional booster dose” to recommend them for people who don’t fall into those categories listed above.

“Protection against infection wanes after the first booster dose,” an ATAGI statement says.

“However, protection against severe disease (rather than all infection) is relatively well maintained, especially in young healthy populations.”

Essentially, ATAGI is saying that while people outside those four groups may get sick from COVID-19, there’s a lower risk they’ll become severely ill from the virus.

“These recommendations for an additional booster dose focus on protecting the most vulnerable groups against severe disease and reducing the potential burden on the healthcare system over the coming months,” ATAGI says.