National leader Simon Bridges has attacked the Government's response to the threat of coronavirus – but officials and experts say our national plan has been working well. So what is it? Science reporter Jamie Morton explains.

Keep it out – and stamp it out.

Those are the two officially-termed phases that New Zealand's public health system has working off over recent weeks under the country's national pandemic plan to combat Covid-19.

And while experts have been critical of the plan themselves – pointing out that New Zealand has ranked just 35th out of 195 countries for pandemic preparedness – they say it's been working well so far, with just three confirmed cases to date.

Advertisement

Yet, with Australia today confirming its first case of community transmission, one leading public health researcher expects it will grow increasingly harder to limit Covid-19's spread here.

Such was the danger level of Covid-19, said the University of Otago's Professor Michael Baker, that we'd have to go back to the influenza crisis of 1918 to find a pandemic quite as threatening.

Focus Live: Third NZ coronavirus case is Auckland man in his 40s whose family recently travelled to Iran

READ MORE:
Coronavirus case: 'Terrified' grandmother worried she's infected others
Coronavirus testing: Five questions answered
Coronavirus: Third coronavirus case in NZ marks the first person-to-person transmission
Coronavirus: Woman reveals what isolation is really like after contact with confirmed patient

"It may not be realised, but I think the level of concern indicates for a very destructive event."

The last century saw just three major pandemics that reached us – in 1918, 1957 and 1968 – and the last sizeable event, the 2009 swine flu pandemic, resulted in 3,175 cases and 19 deaths.

New Zealand's plan

New Zealand has had an Influenza Pandemic action plan since 2006, and this was updated in 2017 to reflect new legislation and population calculations.

It was designed to cope with the worst-case-scenario of a "severe" pandemic – the 1918 episode, which killed 9000 people and infected half the population, being the most disastrous example to date.

New Zealand's standard planning model assumed a severe pandemic wave in which 40 per cent of the population – or more than 1.9 million people - became ill over an eight-week period.

Advertisement

The peak incidence in the model occurred in weeks three to five, when about 1.5 million people − a third of New Zealand's population − would be ill, convalescing or just recovered.

The model also assumed a total case fatality rate of two per cent, within which about 38,000 deaths would occur over the eight-week period, peaking at about 23,500 in week four.

That was compared with New Zealand's normal weekly death rate of around 599.

Yet it still wasn't possible to make such a forecast accurately, given that the pandemic unfolding now might not reflect what played out in 1918.

Baker didn't see the same risk, but said the level of concern from the global health community indicated "for a very destructive event", adding it was possible that half the world's population could become infected.

"In this case, the concern is the case mortality risk, and the proportion of people going into ICU," Baker said.

"We know that it's quite transmissible – but that is based on a pattern of illness, particularly in older people or those with underlying illnesses."

The 1918 influenza infected half the New Zealand population and killed 9000. Photo / File
The 1918 influenza infected half the New Zealand population and killed 9000. Photo / File

Six phases

New Zealand's plan worked off phases, dubbed plan for it; keep it out; stamp it out; manage it; manage it (post-peak); and recover from it.

The plan recently moved from keep it out, when human-to-human transmission of a virus able to cause outbreaks had been verified, to stamp it out, when authorities could release antivirals, order a pandemic vaccine after declaration from the World Health Organisation, and then commence vaccination.

Domestic and international "don't travel" notices could be issued, schools in affected areas could be closed, access to public gatherings restricted – and some areas could even be isolated altogether if needed.

In the fourth phase – assuming multiple clusters of the virus was spreading out of control – authorities would order the pandemic vaccine if they hadn't already, and consider the need for an epidemic notice, or declaring a state of local or national emergency.

Under this crisis scenario, distribution of critical goods and services around the country could be prioritised by Civil Defence.

As demand in a moderate to severe pandemic was likely to exceed the supply of hospital beds, public and private hospitals, too, would need to prioritise admissions and "rationalise non-acute services and review staff rosters", the plan stated.

The capacity to admit people to hospital during the "manage it" phase was likely to be limited during a mild to moderate pandemic - and "considerably constrained" during a severe pandemic.

"It may not be realised, but I think the level of concern indicates for a very destructive event," Otago University's Professor Michael Baker says. Photo / NZ Herald

However, the Ministry of Health has said that just a small proportion of people with Covid-19 – less than 5 per cent - would require intensive care.

New Zealand's 20 DHBs had nearly 180 ICU beds and nearly 270 negative press rooms, including 63 in Counties-Manukau and about 50 in Auckland.

In the fifth phase - in which the wave was decreasing, but the possibility of a resurgence or new wave remained - authorities would move toward restoring normal services, re-opening schools, lifting restrictions on travel and public gatherings, and implementing vaccination programmes.

The final phase focused on recovery and rebuilding population health – and included the option of setting up special recovery offices.

Despite these contingencies, the latest Global Health Security Index still scored New Zealand just 54 out of 100.

It scored zero for some indicators such as "data integration between human/animal/environmental health sectors" and "exercising response plans" – and remained one of the few high-income countries in the world not to have a field epidemiology training programme.

What will happen?

"We don't know what will happen in the future, but I think we should be preparing for a very large health event – or a public health disaster, you could call it," Baker said.

The capacity of New Zealand hospitals would become
The capacity of New Zealand hospitals would become "considerably constrained" in a severe pandemic. Photo / NZME

"Models have been showing that we've been on the trajectory for a global pandemic for a month now."

Baker explained that three big factors mattered: transmissibility, case fatality risk, and controllability.

"We do tend to be looking at the higher end of the transmissibility range, and it's within the bounds of other pandemics we've seen," he said.

"The jury is still out about the basic reproduction number - but it's high enough to assume that it is going to infect maybe half the planet in the next one to two years.

"That seems to be a reasonable expectation, but it might be less, depending on how it affects certain populations.

"As for the second factor – how dangerous it is – we have a rough estimate of a 1 per cent case fatality rate at the moment, but again, that could drop, depending on how our systems respond."

There was also uncertainty about how well it could be controlled: China had demonstrated, for the first time in history, that a pandemic could be tackled in full flight, albeit through brutally tough measures.

"The Chinese experience has made people feel optimistic, but whether that is acceptable or sustainable is another question."

Baker said the Ministry of Health had done a "great job" so far – but the general feeling among his fellow experts was that it would be tough to stop community transmission.

"That's partly because countries overseas have seen that happen now too. So yes, that's what we should be planning for," he said.

"One of the messages that is very important at the moment is that people do change their behaviour. If you are feeling unwell, and have a fever and a cough, particularly, then don't go to work, school or events.

"If people did that really thoroughly, then we could achieve major control of this thing."