New Zealand: We're At Zero Active Cases - But Here's Why That 'Doesn't Mean Much'

These are some of the 'golden rules' of life at alert level 1.

While having no active cases was a "great milestone" the whole point of lockdown and the various control measures was to deal with the other chains of transmission that weren't yet known, he said.

The one remaining case - a person in their 50s from Auckland, linked to the St Margaret's Hospital and Rest Home cluster - was classified as having recovered as of Monday, June 8.

Reaching zero active cases was a sign New Zealand was emerging from the pandemic, which was positive, Baker said.

But that's not to say we won't get another case in the future. "Tail end" cases and potentially unknown chains of transmission could still be cause for concern.

"The active cases ... should all be safely in isolation at home, and so they're not [going to] be infecting anyone."



While reaching zero active cases is great, it doesn't mean that much to public health experts.

There has not been evidence of community spread since April. Most of the country's cases were a result of, or linked to, international travel - 38 per cent and 31 per cent, respectively. The first case that emerged at the end of February was imported, as they had travelled to New Zealand from Tehran, Iran, via Dubai and Bali.

The Ministry of Health's director-general of health, Dr Ashley Bloomfield, has said he is "very confident" community transmission wouldn't return as we begin to ease restrictions.

But Professor Nick Wilson, another public health expert from the University of Otago, explained that reaching zero active cases was never a "key goal" during the pandemic.

"The key goal is [New Zealand] going for a defined time period with no new cases being identified."

Already, New Zealand was on the right track. As of Monday morning, there had been no new cases for 17 days in a row.



Public health experts Professor Michael Baker and Professor Nick Wilson from the University of Otago, Wellington

Baker added that the "long term trend" of having no cases was more interesting than noting the first day of no cases.

He likened it to there being no deaths on the roads over a long weekend. While that would be great to hear, it didn't mean our roads were inherently safer, or that they would stay that way.

"[We] went from exponential rise, to a plateau, and then a steady decline. It's the decline we're looking at."

Elimination wasn't defined by there being zero active cases, or just a week of no new cases, instead, there needed to be an extended period of time without cases emerging. Wilson, Baker and their colleagues estimated the necessary time frame time to be at least a month.

"It would take between 27 and 33 days of no new detected cases of Covid-19 for there to be a 95 per cent probability of epidemic extinction in [New Zealand]," Wilson said.

For that probability to rise to 99 per cent, 37 to 44 days case-free were needed.

However, Baker clarified that this timeframe wasn't from the last reported case - which was how the Ministry of Health presented the data - but instead the first instance of infection for the most recent case.

"The clock is ticking from not the last case, but from the onset of illness in that last case," he explained.

"You've got to look at every one of those cases in terms of what it actually means and when they were likely to get infected.

"If we [had] a case detected tomorrow it wouldn't necessarily mean you've got to start the clock again."

The only reason the clock would need to start again was if the new case was within the community and had no links or traces back to existing cases. The likelihood of that happening was "very low now", however, Wilson pointed out there would be an ongoing risk of transmission aboard inbound aircraft arriving from countries where Covid-19 was still present.

In comparison to other Organisation for Economic Co-operation and Development (OECD) countries, such as Australia, New Zealand's progress and elimination of active cases was positive, Wilson said. And in terms of elimination, New Zealand was closer to reaching that goal than Australia, as evidence of community transmission was still present.

While New Zealand was doing well, it wasn't the first to have no active cases, Baker said.

"I do think New Zealand needs to be a bit more modest in describing its success."'

The US continues leads the world in coronavirus deaths and infections, with more than 100,000 deaths and 1.69 million confirmed cases.

Wilson highlighted Iceland as the only OECD country that was as close as New Zealand in its declaration of being Covid-19-free. However, it did report a new case on May 26. Taiwan might also be able to declare elimination in the near future, he said.

Once elimination was achieved life could become closer to how it was pre-Covid-19, however, there might be some long-lasting changes.

Wilson predicted working from home and video conferencing might become more of a norm in offices, people would maintain increased hand hygiene and cough etiquette to limit the spread of other infectious diseases, and quarantine and border restrictions might be replaced with safer, less-stringent arrangements.



Cabinet was planning to review the situation on June 8 and the prime minister has suggested a move to Alert Level 1 could be made days later.

Looking at the differences between level 2 and level 1, Baker didn't understand the desire to race down, seeing as there wasn't a dramatic difference in the two. One of the main points of difference was the lack of restrictions on social gatherings and businesses within the hospitality industry.

Wilson highlighted two main areas that could be worked on post-elimination: accelerating preparations to reopen travel with other Covid-19-free Pacific Island nations, and accelerating preparations to get an agreement on elimination definitions with Australian health authorities to allow travel to states without the virus.
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