Australia's lockdown measures halt COVID-19 for now

By Dr. Liji Thomas, MDMay 4 2020

A new study from the University of Melbourne finds that measures taken by the Australian public and government have effectively contained the spread of COVID-19 in Australia for the present. The paper is published on the preprint server medRxiv* in May 2020.

The study analyses the unfolding of the epidemic and the ensuing public health response, including the "intensity and timing of public health interventions."

Melbourne, Australia - Apr 13, 2020: Beach Closed due to COVID-19. Coronavirus sign at St Kilda beach. Image Credit: Alex Cimbal / Shutterstock

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

Early Travel Restriction Reduces Importation of Infection

On January 31, 2020, China reported 9,720 cases of COVID-19. However, Australia had only 9 cases that had a travel history or a direct link to Wuhan.

Australia put precautions in place as early as February 1, back when China was the only country where community transmission was reported. All travel from mainland China was restricted, except in the cases of Australian citizens and residents, who were advised to self-quarantine after their arrival.

In addition to this, testing and awareness campaigns became a part of precautionary border measures for arrivals from other countries. These measures were based on a tool developed to evaluate the risk of spread through these means, in early February.

Approximately 200,000 air passengers were expected to land in the country from mainland China. However, due to the restrictions put in place, travel numbers were significantly reduced.

"These restrictions were not intended (and highly unlikely) to prevent the ultimate importation of COVID-19 into Australia.  Their purpose was to delay the establishment of an epidemic, buying valuable time for health authorities to plan and prepare," the researchers explain.

In February, the country only saw 12 cases. However, travel restrictions were expanded in March 2020 to cover other countries with uncontained outbreaks like Italy and Iran.

Preventing Community Spread

However, case numbers began rising in the first two weeks of March, most of them linked to overseas returnees. Localized community transmission was reported in Sydney and Melbourne. Infection rate graphs began to look like those in China, Europe, and the US.

The second half of March saw the Australian government introducing a slew of tighter restrictions step by step, all aimed at reducing existing community spread and preventing it where it was not yet operating. These measures included social distancing measures, mandatory self-quarantine for all international arrivals (which included Australian returnees within the next two weeks), and closed international borders to all countries (except for citizens and residents).

By the end of March, the government advised strict social distancing measures, where people were discouraged from leaving their homes for any but essential reasons. It also prohibited public gatherings with more than two people. It worked - cases began falling again.

Australia Holding Its Own

Australia reported over 6,500 confirmed COVID-19 cases by April 18, 2020, with 67 case fatalities. However, the disease curve has been flattening since late March 2020, with fewer infections being reported each day.

The investigators say, "Our analysis suggests that Australia's combined strategy of early, targeted management of the risk of importation, case targeted interventions, and broad-scale social distancing measures applied prior to the onset of detected widespread community transmission has substantially mitigated the first wave of COVID-19. "

Falling Reproduction Number

Researchers used a reproduction number - the number of people whom an infected COVID-19 patient infects, in the presence of public health measures and normal susceptibility to the virus. If the reproduction number was below 1 in a certain area, researchers could safely assume that there would be a drop in the infection rate. This also meant that hospitals and intensive care units would not be overwhelmed by a high number of simultaneous infections.

"We estimate that the effective reproduction number was likely below 1 (the threshold value for control) in each Australian state since mid-March and forecast that hospital ward and intensive care unit occupancy will remain below capacity thresholds over the next two weeks," researchers said.

A worst-case scenario was avoided, researchers add, where daily demand for ICU beds would have been 35,000 ICU beds at the most by May 2020, much like other countries that failed to contain the outbreak. This would have far overwhelmed Australia's health system capacity of approximately 2,200 ICU beds.

Cautious Relaxations To Keep The Curve Flat

The team warned against premature relaxation of containment measures, especially in places where localized transmission has already been reported, as well as high-risk areas like nursing homes for elderly patients, which have reported a high global fatality rate.

While the case detection rate among symptomatic patients is above 77% in Australia, the number of asymptomatic, mild, and undiagnosed infections remains largely unknown, the researchers added. The presence of a high number of asymptomatic cases has been a thorn in the flesh for many countries grappling with the epidemic.

Even if there were a large number of such cases, the Australian population would still be extremely vulnerable to infection because of the low prevalence of COVID-19 so far. However, the time Australia has bought with its early action may empower it to be more prepared when the wave hits, the researchers conclude.

As of today, May 4, 2020, Australia has reported 6,801 cases and 95 deaths. 5,817 cases are reported as recovered. Over 633,000 tests for COVID-19 have been conducted to date.

"For now, Australia is one of the few countries fortunate enough to be able to plan the next steps from a position of relative calm as opposed to crisis," concludes the report.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources