Time for a clear national COVID‐19 strategy

To the Editor: Pandemic responses across the world have been highly reactive. However, there remain only three strategic options to managing coronavirus disease 2019 (COVID‐19): mitigation, suppression and elimination (Box).2 With the promise of efficacious new vaccines, mitigation is appropriately not considered as part of Australia’s national strategy. However, our stated goal of achieving “no community transmission” remains poorly defined and risks missing important distinctions between elimination and suppression.3

Effective elimination is dependent both on getting to zero local cases and then staying there, with any new transmission chains immediately halted. All jurisdictions of Australia have now achieved elimination over significant periods, even without articulating this as their strategy. By comparison to suppression, greater relaxation of restrictions may well be allowable under an elimination approach if vigilance is maintained, as New Zealand has demonstrated.4 Although the challenges of ensuring quarantine of returning travellers are well recognised, this is an essential aspect of maintaining elimination and increases in importance as distancing restrictions are eased.

Australia’s current strategy appears to imply suppression, with some virus circulating but with case numbers at manageable levels. Whether suppression has been achieved can be monitored by maintaining an effective reproduction number of no greater than one, or equivalently by ensuring the epidemic curve of new community cases is not upsloping. Importantly, the reproduction number and the rate of new cases at any point in time are unrelated — we could have effective suppression and a reproduction number of one with daily case rates of five, ten or 50. Our definition of no community transmission appears to imply complete identification of transmission chains with no “mystery cases”, regardless of the number of new cases. These considerations are important in determining whether we have full visibility of the epidemic and effective contact tracing but do not determine the reproduction number.

The rapid spread of the virus necessitates a public health strategy that is clear, robust and agile. Improved control combined with the increasingly clear seasonality of the virus5 suggest that control can be maintained throughout the summer. However, if vaccination has not been widely distributed before winter 2021 and we do not make clear choices, further major outbreaks remain likely.