The current spike of COVID-19 infections in Melbourne is a predictable consequence of government responses to the pandemic, James Trauer writes.
When looking to the Melbourne-centred second wave of coronavirus infections, Australians should only really be surprised that outbreaks of the same scale haven’t occurred elsewhere in the country. Given the government’s response to the pandemic, this was equally foreseeable just a few weeks ago.
The fundamental problem with Australia’s COVID-19 response has been that its stated goal was to achieve suppression, but it failed to put in place an approach that recognised the realities of this strategy. While the government’s response has had considerable success in many regions of Australia, this success has only been achieved by accidentally eliminating the virus, rather than continuing to suppress its transmission, as per the original plan.
Although this distinction is well-known to epidemiologists, it should now be clear that there is a major difference between reducing community transmission to low, or even very low levels, and totally eliminating transmission from our communities.
Early in the pandemic, several approaches to managing the virus were proposed, and in the absence of a vaccine, only four possible options are available to policymakers. First, an unmitigated or only partially restrained epidemic, second, allowing controlled transmission in lower risk younger people, third, suppression, as was Australia’s stated goal, and fourth, total elimination.
Modelling from Imperial College London demonstrated the horrors that would be seen if any government pursued the first option, some of which quickly played out in Italy and elsewhere in Europe. In Australia, there has also been little appetite for the second option, although many other countries may not have the resources needed to sustain either of the last two options over the coming months.
The country therefore went with suppression, citing the high costs of an elimination approach, and claiming it was unlikely to succeed. From early May, its approach has consisted of a three step framework for rapidly releasing restrictions, built around the concept of ‘continued suppression’ rather than pushing for complete elimination of the virus.
However, this approach is inconsistent with a clear understanding of the epidemiological situation, and several basic epidemiological principles need to be considered before the government can develop a workable strategy.
First, successful control has ensured that the vast majority of the Australian population remain fully susceptible to infection. This means the community is a long way from herd immunity. Although racing to herd immunity in an uncontrolled fashion would be disastrous, it is important to keep reinforcing that a lack of herd immunity is what underpins the current dilemma.
Because of this, Australia remains in an extremely fragile situation with the potential for exponential infection growth if suppression is not maintained. In the absence of elimination, exponential growth is virtually certain where restrictions have relaxed to the point that the average number of secondary infections caused by each infected person exceeds one.
The only thing that can protect us from this exponential growth is total elimination – if there is no virus, there can be no transmission.
Although complete elimination seemed unlikely to work as a control strategy until recently, the success of most jurisdictions in Australia and New Zealand in reaching zero locally-acquired cases has been remarkable, and suggests it could work as a national strategy.
For some places, elimination has been surprisingly effective, despite never being the plan. While implementing a flawed plan to maintain suppression, many communities, and in some cases entire states, have accidentally succeeded in eliminating the virus entirely.
Meanwhile though, control has failed in Melbourne. This situation is complex, with specific failures, such as the breakdown of quarantine, large family gatherings, and multiple highly localised outbreaks blamed for the loss of control. Nevertheless, with Victoria reporting zero cases on only a handful of days in early June, it is unlikely it ever achieved elimination, as other states managed, while the rapid release of lockdown measures was also inconsistent with a suppression approach.
Although much of this was predictable, policymakers and leaders still need to learn from these events and recognise that suppression and elimination are distinct.
Each strategy has major drawbacks that are essential to stress: elimination requires stringent controls on travel, large economic costs, and maintaining high public health capacity for an aggressive response to small outbreaks.
Meanwhile, suppression carries the risk that the community can never truly emerge from lockdown until a vaccine is developed, as neither herd immunity nor a totally virus-free community will materialise under the strategy.
Although the economic costs are often cited as an argument for choosing suppression, if restrictions can be released to a greater extent after elimination has been achieved, suppression could have greater economic effects.
Currently, Australia’s leaders have not accepted that, without a vaccine, a suppression strategy is inconsistent with a complete return to normality.
Achieving suppression should be pursued by gradually and sequentially releasing restrictions while the virus is still transmitting, and assessing epidemic control at each stage. By taking such a staged approach to suppression, policymakers would gain more information on how far they can release restrictions.
Australia needs a clear plan, with both suppression and elimination on the table. Otherwise, it could be left lurching between lockdowns and easing restrictions for months or years to come.
Leaders cannot continue trying to sit on the fence, nor ignore the shortcomings of the suppression strategy, and the government must explicitly choose either elimination or suppression as the national outlook. Then, each jurisdiction can plan policy for its own region, develop that plan knowing the environment it will be working in, and hopefully succeed in its fight against the virus.