Health officers consider restrictions beyond stage 3

The road map progressively lifts restrictions on gatherings from 20 people, to 50, to 100 at step 3, but doesn't say what happens after that.

On Monday, the national health advisory group discussed how to limit the spread of the virus beyond stage 3, through a cap on numbers at mass events or restrictions on the density of gatherings.

The new focus comes as numbers of coronavirus cases continue to fall, with no obvious increase yet from the lifting of restrictions which began about four weeks ago. Just over three weeks ago, Canberra restaurants began opening for 10 diners at a time, and now they are serving 20. NSW has moved to 50.

Deputy chief health officer Nick Coatsworth said in the past week 61 new cases had been diagnosed across the country, down from 91 the week before. Of the new cases, nearly 70 per cent were acquired overseas.

Australia has fewer than 460 active cases, with 19 people in hospital, three in intensive care and two on ventilators on Monday.

Asked about the underlying case numbers, where people have the infection without knowing it, or have cleared the infection without ever being tested, Dr Coatsworth said those numbers were likely to be very small, given that less than one in 200 tests were positive.

"You have to assume ... that it's very unlikely that there's a large bit of the iceberg that we can't see," he said in an interview.

"If that were the case you would see the tip being a lot more cases in hospital, more cases intensive care, that's what the tip is. So if those numbers are very small, then the number of community cases has to be small as well."

The road map agreed by the national cabinet on May 8 looked to stage 3 being in place in July. In stage 3, gatherings of up to 100 people are allowed, with people returning to the office, universities back to face-to-face-teaching, and consideration given to allowing international students in time for semester 2.

Dr Coatsworth said the chief health officers had discussed the principles of maintaining social distancing after stage 3, when ongoing caps on numbers and the density of gatherings were likely for the foreseeable future until a vaccine or effective treatment became available. Some restrictions were likely to remain for gatherings where it was difficult to trace contacts and where there was a high number of people mixing from different parts of the community.

But firm numbers were yet to be settled, and in deciding numbers it was important to acknowledge the difference between a sports stadium at quarter capacity and a nightclub with fewer people but where they might be clustered around a bar, he said.

The group had not discussed international students on Monday, he said.

New Zealand is lifting all restrictions on movement and gatherings with no coronavirus cases in the country, and the public health professors who prepared the coronavirus modelling for that country have now recommended that face masks be compulsory on public transport and on airplanes.

But Dr Coatsworth said in Australia face masks were not recommended for the public. They were likely to be useful in countries were the prevalence was far higher than in Australia and where there was a high probability of encountering someone with COVID-19 in the street, he said.

Nor does the national health advisory group recommend self-isolation for people, who attend the black lives matter protests, but Dr Coatsworth said, as with all Australians, protesters should watch carefully for symptoms and get tested if any developed any.

Given the incubation period, it would be at least two weeks before authorities could tell whether the protests had any impact on case numbers.