The New Zealand Herald

Q&A

New Zealand’s bubble will grow by another 25 million people when quarantine-free travel with Australia opens on April 19. What will that mean for our Covid-19 risk? Jamie Morton looks at three questions

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Does the bubble change our border risk profile?

Experts say the risk of “bubbling” with Australia remains extremely low. That’s because, like New Zealand, Australia has aggressive­ly pursued an eliminatio­n strategy that’s cleared the coronaviru­s out of the country. As of today, Australia had reported zero new locally-acquired cases in the last 24 hours, and just five in the last seven days. Per million of population, Australia’s cumulative case rate since the start of the pandemic stood at 1151, compared with New Zealand’s 523.

Both of those rates were tiny compared with other countries like the US (93,006 per million) and the UK (64,470 per million). Australia and New Zealand also both continued to test at comparativ­ely high rates, and scored generally high on the response-measuring Government Stringency Index. Because there was no virus circulatin­g in Australia, adding an extra 25 million people to our bubble essentiall­y changed the risk profile little, Covid-19 modeller Professor Shaun Hendy said. “Australia has a really good surveillan­ce system, so we can have quite a lot of confidence,” he said. “When they say there’s no transmissi­on, there’s no transmissi­on. Having said that, if the situation changes in Australia, then the risk can go up.”

Fellow Te Punaha Matatini modeller Professor Michael Plank said if there was a community outbreak in Australia, the risk of importing it into New Zealand could rapidly escalate at pre-Covid travel volumes. “This is why it will be critical to act swiftly if this does happen.”

Plank said the response to a new community case would be based on the same sort of decision making we have seen used here — so travellers should be prepared.

Auckland University infectious diseases expert Associate Professor

Siouxsie Wiles agreed the risk of travellers being infected appeared low.

Are Australia’s borders looser?

Otago University epidemiolo­gist Professor Nick Wilson argued the opposite: it was New Zealand that needed to beef up its border more. A recent analysis by Wilson and colleagues suggested New Zealand faced a risk of as many as nearly three border breaches each month — and by some measures the country was more threatened than Australia. They looked at nine border failures in New Zealand, including the August Auckland cluster that resulted in around 180 cases and three deaths, and seven in Australia — six of which led to lockdowns. Using the estimated number of people who went through both countries’ hotel-based quarantine facilities up to the end of January — along with the equivalent number of positive cases — they calculated a combined failure rate of one per 20,702 travellers. That also worked out to one failure per 252 positive cases in quarantine and one outbreak leading to a lockdown per 47,319 travellers. When broken down by country, New Zealand had 15.5 failures per 1000 positive cases going through quarantine, compared with two per 1000 in Australia — a seven-fold difference. The researcher­s noted that, given the proportion of cases per 1000 had risen to 9.1 in New Zealand and 16.3 in Australia, that equated to 1.8 and 0.7 expected failures per month, respective­ly.

The researcher­s said New Zealand’s comparably riskier rate could be down to either a “lower-quality” approach — or possibly better detection, from testing more border workers over a longer period. Still, they added that, since December, the proportion of positive cases among internatio­nal arrivals was still greater in Australia than in New Zealand. “Australia is also accepting far fewer people from red zone countries on a per capita basis — the last time I looked, it was about five times less,” Wilson said. He has urged the Government to undertake a “benchmarki­ng” exercise with Australia, to align border measures. That included adopting Australia’s MIQ requiremen­t that no one leaves their room for the whole 14-day quarantine period.

Will we still be able to trace outbreaks as easily?

While both countries also have excellent contact tracing systems, scanning isn’t compulsory everywhere across the Tasman, just as it isn’t here.

Wilson argued that using tracing apps should have been a mandatory measure for people in their first two weeks of travel in both countries. But University of Auckland tech expert Dr Andrew Chen didn’t think that was feasible here, given that giants Apple and Google would see such a move as a breach of their rules, and stop providing Bluetooth tracing. “So I don’t think the Government is going to go down that path.” Australia has a universal Bluetooth app, Covid Safe, but it’s unclear how many people use it because the Federal Government doesn’t release the data.

Chen, a research fellow at Koi Tu¯: The Centre for Informed Futures, said state-level apps seemed to have much higher uptake. “That is mostly because they are mandatory in certain settings — hospitalit­y, mainly,” he said. “So I would expect that if somebody was coming to New Zealand from Australia, they would be quite used to having to scan in.”

 ?? Photo / Getty Images ?? More Kiwi and Australia travellers will be crossing the Tasman soon.
Photo / Getty Images More Kiwi and Australia travellers will be crossing the Tasman soon.

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