The adult population of Australia is predominantly double vaccinated against COVID-19, but with rapidly climbing case numbers, authorities are encouraging anyone eligible to get a booster shot.

The current health advice says if you’re over 18 and had your second dose of vaccine four or more months ago, you are eligible for a third.

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When booking a booster you may be asked to choose between the Pfizer or Moderna vaccine, but which is better?

Chair in epidemiology at Deakin University’s Institute for Health Transformation Professor Catherine Bennett told The New Daily the best booster to choose is the one that is available.

Recent studies show both Pfizer and Moderna work as a booster against COVID-19.

“The good news is they work just as well whether you had Pfizer or AstraZeneca the first time,” Professor Bennett said.

“The boosters really do lift your immune response.”

ATAGI considers the Moderna and Pfizer vaccines to be “equally acceptable” as booster shots for adults, according to the Department of Health.

When it comes to choosing between them, it may come down to personal preference.

People might choose Pfizer because they have had it before, or if they experienced side effects they may be inclined to switch.

Professor Bennett said it’s important to note the Moderna booster is a lower dose than the initial two shots and is now more similar to Pfizer in terms of local, short-term reactions.

Moderna has the edge, slightly, when you look at the data, but there’s not a lot of difference in it, she said.

“If you’re in an area where there’s a lot of Omicron circulating, then whatever booster you can get is the good booster.”

Professor Bennett also pointed out that Pfizer and Moderna are mRNA vaccines.

“So it’s really only the AstraZeneca primary source people who are ‘switching’ – in terms of vaccine type – and it is safe and effective to do so,” she said.

“The answer is they both work well. Whatever one you can get access to is the best one to have.”