You will have heard a lot about ‘modelling’ lately. That’s what epidemiologists do to map out how a disease may spread through a population.

These models, which authorities use to plan their response to an outbreak, explore possible scenarios based on available data. They may suggest, for example, the number of infections and deaths that are likely if a particular policy or strategy is put into place.

Professor Tony Blakely, an epidemiologist at the University of Melbourne, is among those modelling the spread of COVID-19.

Writing for the university’s publication, Pursuit, he noted that the number of new cases in Australia has slowed, which buys authorities a little more time to decide what to do next.

Simple ways to protect yourself from COVID-19.

Prof Blakely mapped out three possible paths they could take:

1. “We could see a late and valiant attempt at elimination – with likely low chance of success.”

2. “Flattening the curve towards herd immunity – with our health services better stocked with equipment and hopefully more evidence on effective treatments.”

3. “Continue squashing the curve for months and months till sometime in 2021 (with a muted epidemic or two along the way) until a vaccine is available – with less mortality but also much greater societal and economic cost.”

None of these options is perfect; each involves a significant cost, either to the health system, the economy or the community. And it remains to be seen which would be the most effective.

But to get a sense of what our leaders are wrestling with right now, let’s peer down Blakely’s three paths.

Elimination

Elimination basically means driving the number of cases to zero using strict physical distancing and strict border control.

John Daley, Chief Executive Officer of the Grattan Institute, recently explained via The Conversation that an elimination scenario involves only maintaining essential services, including the food supply chain and utilities. Everything else — schools, universities, public transport and non-essential retail — must be closed, and people must be confined to their homes as much as possible.

So essentially, something closer to a Stage 4 lockdown, like those occurring in New Zealand.

“Police should visibly enforce the lockdown, and all confirmed cases should be housed in government-controlled facilities,” Daley wrote.

“Once infections are at zero — and stay there for a fortnight or so to ensure there are no asymptomatic cases — economic and social activity can restart sequentially, although international borders would have to remain closed to passenger traffic until there is a vaccine.”

When he penned the article in March, Daley speculated that Australia would only have to enforce this kind of stricter shutdown for eight to 12 weeks. But the border closures would have to last far longer.

“Until a vaccine is deployed — and we’re punting that there will be a vaccine — there will be no meaningful international travel, tourism or students for at least 12 months,” he wrote.

“[But it] would allow domestic travel and tourism, hospitality, and other domestic activity once the shutdown was over.”

To have the best chance of success, this approach needs to happen early in a country’s outbreak (New Zealand, for example, entered lockdown on March 25 when it had just 205 cases). Prof Blakely argued that it may be too late for Australia.

Flatten the curve (herd immunity)

As Prof Blakely explained in Pursuit, this approach is the ‘ride it out’ tactic. It aims to reduce harm from the pandemic while slowly building up herd immunity.

Herd immunity involves a large proportion of the population becoming immune to a disease, and therefore stopping its spread.

Ideally, that would happen via a COVID-19 vaccine, but that’s likely 12-18 months away. So, in the meantime, flattening the curve would rely on people developing immunity through infection (once a person has the virus, their body develops antibodies that help protect it from catching it again).

‘Flattening the curve’ refers to stabilising the number of new cases a day, so that the line on an epidemic graph like this one… well, flattens. South Korea, for example, is flattening its curve, while the USA is still on an exponential climb.

This approach means allowing a lot of people — roughly 60 per cent — to get infected. But implementing measures, such as shutdowns and physical distancing, to control how quickly that happens. This is crucial to ensure that hospitals don’t become overwhelmed.

Australia doesn’t currently have a high infection rate, so taking this approach would likely involve loosening social distancing regulations initially “to get the daily cases up”, then tightening them again.

One way that could happen, Prof Blakely noted, would be to allow young and healthy people (who are more likely to recover fully) to return to work, while physically isolating elderly people and those with chronic conditions.

Prof Blakely crunched the numbers and calculated that, under current conditions, this kind of ‘ride it out’ approach would take until February. But he speculated that by formally adopting the strategy and making key adaptions, it could be as little as six months.

“For example, ‘just’ doubling again ICU capacity to 8,000 beds will bring the end of a managed epidemic back to October this year – if we were to loosen up controls now,” he wrote.

Squash the curve

While some of Australia’s policies are closer to an elimination strategy, ‘squashing the curve’ seems to be the road Australia is currently heading down.

It’s about keeping case numbers as low as possible until there’s a solution – i.e. a COVID-19 vaccine, which again, is at least 12 months away.

Until then, this approach would likely involve ongoing physical distancing measures, which would be periodically dialled up to squash spikes in new cases that emerge via community transmission.

It’s a long-game approach that would potentially prevent thousands from dying from COVID-19, but would result in enormous economic fallout and significant disruption to daily life.

Speaking to News Corp, Prof Blakely said there is also a risk with this approach of deaths associated with long-term lockdown including suicide and domestic violence homicides.

“Many of us are concerned and are crunching the numbers to work out the death toll for squashing the curve … and it could be just as bad as for COVID-19,” he said.

Read more on COVID-19:

• What you need to know about COVID-19 today, Tuesday April 7.
• No weddings and a form to leave the house: What a Stage 4 COVID-19 shutdown could look like.
• Three reasons why Jacinda Ardern’s coronavirus response has been a masterclass in crisis leadership.

To protect yourself and the community from COVID-19, remain in your home unless strictly necessary, keep at least 1.5 metres away from other people, regularly wash your hands and avoid touching your face.

If you are sick and believe you have symptoms of COVID-19, call your GP ahead of time to book an appointment. Or call the national Coronavirus Health Information Line for advice on 1800 020 080. If you are experiencing a medical emergency, call 000.

To keep up to date with the latest information, please visit the Department of Health website.