Coronavirus: How safe is a trans-Tasman bubble

Deputy Prime Minister Winston Peters says Australia has done extraordinarily well in combating COVID-19 and, in some places, it's been better than New Zealand. 

He made the call on Thursday as he again called for the trans-Tasman bubble to open as soon as possible. 

If a bubble is opened with Australia there are two things useful for Kiwis to know: the first is the risk of an infected Australian coming to New Zealand, and the second is which states are risky if you visit.

One way to get an indication of risk is to look at the number of active cases in each Australian state. New South Wales currently has the largest number of cases (378), but when you take population into account, Tasmania comes out as one of the higher-risk states.

Victoria has 60 active cases, both Tasmania and Western Australia have 12, Queensland has seven and South Australia has one. ACT and Northern Territory both have no active cases. Comparatively, New Zealand has eight.

But Otago University epidemiologist Professor Michael Baker warns that although the numbers in Australia are low doesn't mean there's also a low risk. 

"Australia is still not committed at a federal level to the same elimination strategy that New Zealand's got, and I think if they don't commit to that, that is still a barrier," he said.

And Australian epidemiologist Mary-Louise McLaws says opening the border is a step too far.

"We shouldn't be opening up our germ bubble until both sides of this germ bubble are safe, and I would say that Australian epidemiology suggests we are not safe enough for you to come over yet - or for you to receive us."

But Peters says some parts of Australia have done a better job of eliminating the virus than New Zealand has.

"In places like Queensland, which has got a greater population than ours, their performance exceeds ours."

He's also not worried that nearly nine percent of Australia's cases are from community transmission - where the source of the virus cannot be tracked. 

"I don't think that is an impediment. I find it a statement of honesty."

Australia is opening its ski fields in the hope of trans-Tasman tourism starting up by the July school holidays, but Prime Minister Jacinda Ardern said on Thursday that "September is realistic".