Early lab tests show the Pfizer vaccine booster appears to offer protection against the Omicron variant of COVID-19, despite the initial two doses being less effective.

Pfizer and its partner BioNTech said a third dose of their COVID-19 vaccine produced a 25-fold increase in the levels of antibodies capable of fighting off Omicron.

Meanwhile, Australian medical regulators have granted provisional approval to the Moderna vaccine to be used as a booster for those over the age of 18.

Michael Azrak, the Australian general manager with Moderna said pending Atagi’s recommendation, anyone who has the Pfizer or AstraZeneca vaccine will be able to get the Moderna booster.

Azrak told ABC News preliminary findings are promising and work on Moderna vaccine effectiveness against Omicron is ongoing.

“It’s encouraging what we’re seeing overnight, I think with all strains and variants we’ve seen it does take a few weeks to really assess it. So the data is optimistic [but] I’d be cautious right now,” he said.

“What we are doing as Moderna is looking at all fronts, so we’ve got a three prong strategy, one is looking at our current vaccine and the boosters at two different dose levels. We’ve got multivariant specific doses in debelopment, and an Omicron specific dose [in development].”