ECONOMIC, biosecurity and animal disease experts are calling for immediate and stronger physical distancing measures to stop an exponential spike in coronavirus cases.

New modelling from experts at ANU and the University of Melbourne shows Australia’s rate of COVID-19 infections is doubling about every seven days, and, it will soon double every few days without sufficient physical distancing.

This is down from a doubling every four days a week ago, experts say, but warn that without adequate control measures and physical distancing, which Australia has started to initiate, the infection rate could rise as high as 20 persons per 100.

In the absence of sufficient physical distancing, possibly up to one-in-five Australians could be infected, resulting in 48,000 additional premature deaths, they say.

Prof Tom Kompas from the University of Melbourne and Prof Quentin Grafton from ANU have also tracked infection rates against physical distancing measures.

“The data now tells us cases are currently doubling about every seven days in Australia, and although the daily rate of growth in infected cases has now decreased to 10 per cent, the growth pattern is still exponential,” Prof Kompas says.

“With our modelling, we project Australia will have between 5080 to 5970 cases at 6pm on April 1 – with the most likely number being 5220.

“For April 2 the range is 5510 to 6835, with 5715 most likely.”

Prof Grafton says the current rate of infection, until the past few days, is based on a lack of severe physical distancing, especially from some who have failed to observe self-isolation, which is needed to slow down community transmissions.

“The growth in infections over the next week or so is essentially locked in until we change how we physically distance ourselves from people outside our household,” Prof Grafton says.

“If we act today, then we may end up with an infection rate of one person in every 100. This is about the infection rate that China ended up with.

“By comparison, if we fail to control the infection and it continues to grow exponentially, Australia could end up with an infection rate of 20 persons per 100. This is the worst case and is not what we would expect.”

The researchers have also modelled potential premature deaths based on a mortality rate of one per cent.

“If we assume a mortality rate of one per cent, then not acting today to ensure sufficient physical distancing in Australia could, in the worst case, result in an additional 48,000 premature deaths,” Prof Kompas says.

“This is equivalent to about 30 per cent of the current annual deaths in Australia.

“These deaths would be clustered in the old and those with co-morbidities, including many in remote indigenous communities if such places are not adequately protected.”

Prof Grafton says Australia needs to implement stronger lockdowns.

“While the future is uncertain, the outcomes of exponential growth are not,” he says.

“Not imposing a lockdown or equivalent measures comes at the cost of a higher infection rate which also means more non COVID-19 patients may die because there may be insufficient beds, medical equipment or staff to look after them.

“The low-risk approach to saving lives is for Australia to copy what New Zealand and the UK are already doing and to impose a ‘lockdown’ to ensure we have sufficient physical distancing.

“With much more testing and tracking of those with the virus, Australia can also have an exit strategy out of a ‘lockdown’ within a few weeks so that the infection does not bounce back.”

Their results are detailed in the specialist ANU publication Policy Forum.