Australians will consider further vaccination against COVID-19 with new booster recommendations to be made ahead of winter.
The Australian Technical Advisory Group on Immunisation (ATAGI) is expected to make a decision on the fifth dose within weeks.
Currently, only those who are severely immunocompromised and over 16, are eligible to get the fifth COVID-19 jab.
As federal authorities prepare to recommend a fifth jab, what happens if you have skipped a dose?
Here's what we know so far.
What if I haven't had my fourth dose yet?
"We really need to think about how recent someone's last vaccine was, rather than how many doses they have had," Monash University associate professor James Trauer says.
"Evidence for the fourth dose was that people were protected for a few months, but that the protection waned back to the level we would see for three doses relatively quickly.
"So these repeated boosters seem to be providing a window of extra protection for a few months.
"This protection is likely to be quite important for the elderly and those with medical conditions, and so we do need to be looking at repeated vaccination as we head into waves of transmission."
What are the recommended intervals between booster doses?
Three months is the recommended time between completing the primary COVID-19 vaccine course and the first booster.
The recommended interval between the first booster dose and a second booster dose (for those who are recommended to receive a second booster dose) is also three months.
ATAGI advises there is no upper time limit for the administration of a booster dose, but notes vaccine effectiveness wanes over time.
What vaccine am I eligible for?
For adults under 60, Pfizer, Moderna, or Novavax are preferred by ATAGI over AstraZeneca for the first two doses, while there is no preferred brand for people over 60.
For pregnant women, Pfizer and Moderna are recommended and Novavax is also an option, but AstraZeneca is not preferred.
When it comes to kids between six months and five years old, COVID vaccines are only recommended for those who are severely immunocompromised, who have a disability or those who have a higher risk of severe COVID-19.
When it comes to what kind of booster you get, the Pfizer vaccine is the only one that is approved for kids from five to 17.
There are more options for adults: Pfizer original, Pfizer bivalent, Moderna original and Moderna bivalent are all available.
And although it is not the preferred option, AstraZeneca and Novavax can be used as boosters for adults in certain circumstances.
While it not TGA-registered, Novavax can be used as a booster for a person who is at least 12 years old when no other brand is suitable for them.
The USA wants a one-shot approach to COVID-19 vaccination, could this happen in Australia?
The Food and Drug Administration's (FDA) advisory committee voted unanimously in favour of a one-shot COVID-19 vaccine approach in the USA.
Because COVID-19 is clearly not going away, Dr Trauer says it will be important to shift towards longer-term, sustainable policies in the future.
"Australia is a little behind the USA in having not had community transmission for as long, but we should be looking at these changes soon," he says.
"However, there are still significant issues with this because we have not yet seen COVID-19 transmission settle into a predictable seasonal pattern yet, and the waves of transmission still appear to be largely driven by new subvariants."
