Canberra, Nov 25 (IANS): An Australian expert warned that the country may be in the grip of a new wave of Covid-19 cases, and booster shots are critical to ensure freedom across the country.

Currently, anyone who has had two doses of a coronavirus vaccine is considered fully vaccinated in Australia, granting them freedom such as interstate and international travel and entry into hospitality venues and large gatherings, Xinhua news agency reported.

However, infectious diseases expert Raina MacIntyre said on Thursday that two doses might not be enough.

"The immunity from two doses of vaccine, whether it's AstraZeneca or Pfizer, starts to wane after a few months," MacIntyre told Nine Network television.

"We need to start thinking ourselves as fully vaccinated if we've had three doses."

Australia's booster vaccine rollout began on November 8, with third doses available for anyone aged 18 and older six months after their second shot.

There were more than 1,500 new locally-acquired Covid-19 infections reported across Australia on Thursday and five deaths.

The Northern Territory (NT) recorded only one new case -- a teenager from the Binjari Aboriginal community who authorities believed was in quarantine.