Health authorities are looking at dual tests which check for flu and COVID-19 — as well as fourth doses of COVID-19 vaccine — to make winter safer for the elderly.

The work comes as Australia’s COVID-19 vaccine rollout passed another milestone, with 50 per cent of children aged five to 11 having received their first dose.

The figure was reached on Monday, with more than 1.1 million children in the cohort being vaccinated.

The vaccine rollout for young children started in early January and the age-group halfway mark comes days after a second type of inoculation was approved for children.

The dual COVID-flu tests are of interest particularly in terms of elderly and frail people having significant respiratory symptoms.

Knowing whether the person has flu or COVID-19 will ensure they get the appropriate treatment.

Health officials say a lot of planning and thought is also going into whether vulnerable people will need a fourth dose.

A final plan would require the nod from the Australian Technical Advisory Group on Immunisation giving approval.

A federal health department spokeswoman told AAP that ATAGI was constantly examining vaccine data.

“ATAGI continues to monitor evidence emerging from medical research on the effectiveness of the COVID-19 vaccines both locally and internationally,” the spokeswoman said.

“ATAGI will update its advice and recommendations accordingly.”

Meanwhile, more than 11.4 million booster doses have been administered across the country, or more than 63 per cent of the eligible population aged 16 and over.

Ahead of its hard border reopening to the rest of the country this week, Western Australia registered its highest daily total of COVID-19 cases, with 1140 new infections.

The state’s border will come down on Thursday, after months of being isolated from eastern states.

A further 12 COVID-deaths were reported on Monday across the country.

Of those, six were from NSW, three in Victoria, as well as one in Queensland, South Australia and the ACT.

There were more than 19,000 new infections detected nationally in the latest reporting period.

Across the country there are 2001 patients in hospital for COVID – mostly in NSW.