Australia’s immunisation regulator cannot rule out four, or even five, doses of COVID-19 vaccine being required to be considered “up to date”.

Appearing before a Senate estimates committee on Wednesday, Australian Technical Advisory Group on Immunisation chair, Nigel Crawford, said his organisation would continue to monitor data from countries administering four doses.

Health Minister Greg Hunt announced last week three doses were now required to be considered up to date, while Professor Crawford told the hearing some immunocompromised patients were already recommended four vaccine doses.

Asked by Liberal senator Alex Antic if he could assure Australians they would not be required to get four or even five doses to be considered up to date, Professor Crawford could offer no such guarantee.

“Countries like Israel have already recommended a fourth dose and we need to look at that international data and see the impact, and what the new variant vaccines look like,” he said.

“ATAGI is constantly reviewing the evidence … that advice may change over time. It is a possibility but there’s no current recommendation to that effect.”

Elsewhere at Senate estimates, Australia’s vaccine rollout head Lieutenant-General John Frewen said the Indigenous vaccination gap had reduced by some 12 per cent, with 77.4 per cent of Indigenous Australians double-vaccinated.

Almost 60 per cent of eligible Australians have had three doses, and 48.1 per cent of children aged between five and 11 years old have had their first dose.

Some 64 COVID-related deaths were recorded on Wednesday with 27 from NSW, 18 in Victoria, 12 in Queensland, four in South Australia and three in the Northern Territory.

There were 29,229 COVID cases across the country.

Three federal MPs tested positive for COVID on Wednesday – junior ministers Kevin Hogan and Scott Buchholz and Labor MP Anika Wells.