The Morrison government has resisted calls from journalists, academics and healthcare workers to publicly share the pandemic modelling the Australian Health Protection Principal Committee has used to recommend its increasingly tough measures. Loading But on Monday Deputy Chief Medical Officer Paul Kelly said he would “unlock” the modelling this week. It is unclear whether the government will release the modelling in full. One New Zealand report outlines the potential worse case health impacts of COVID-19 if eradication fails and confirmed cases weren't isolated, social distancing measures were only in place for two months and winter accelerated the spread of the virus by 50 per cent. It assumes the epidemic would peak in early July and the virus would have an R0 of 3.5 (for every case it could spread to 3.5 more people on average). NZ’s R0 will likely be lower than the World Health Organisation’s R0 range of 2-2.5 because of its relatively low population density and low smoking rates, the authors say.

In worse-case modelling, New Zealand's ICUs would become overwhelmed and only 25 per cent of critical care patients would be saved. “This death toll would far exceed the death toll for NZ from World War One (18,000 deaths) and from the 1918 influenza pandemic (9000 deaths),” the report found. Loading Replay Replay video Play video Play video More than two-thirds of New Zealand's 5 million people would develop symptoms (3.32 million people) and 146,000 would need to be hospitalised. Roughly 36,600 would need an ICU bed and 50 per cent would need ventilators. The country has only 221 ICU beds, which an ICU expert told the modellers could be doubled in “extreme circumstances”. The death toll did not include people who couldn’t receive normal care for other serious conditions such as heart attacks because the health system was struggling to cope with COVID-19 cases.

It also flagged other “worse case scenarios” such as hospital staff strikes over personal protective equipment shortages. Another NZ report suggested that if NZ's interventions were intense enough, the epidemic peak could be pushed out to next year, when hopefully a vaccine would be available. It modelled the effects of three R0 scenarios (1.5, 2.5 and 3.5) and various intensity levels of "general contact reduction" interventions over two, six and nine months. Another report concluded that assuming the least severe scenario of R0 1.5, 92,500 people would need to be hospitalised, 14,400 people admitted to ICU, 6480 ventilated and 8190 people would die.

A more severe R0 of 2 would lead to 124,000 hospitalisations, 19,400 ICU admissions (8690 on ventilators) and 10,983 deaths (0.22 per cent). The majority would be people aged over 65. Loading The report concluded the scale of these hospitalisations and deaths “may justify substantive societal and governmental resources being put into prevention” and "very intensive control measures". Within days of this report being finalised on March 16, Prime Minister Jacinda Ardern declared a national emergency and announced a lockdown. Chief executive of New Zealand’s health ministry Dr Ashley Bloomfield said the modelling showed that without the government's actions, "the uncontrolled spread of COVID-19 would exact a high price in New Zealand".