Grant McArthur: Lockdown can be avoided if virus doesn’t break Whittlesea containment lines

It’s possible we can contain this latest cluster, but lockdowns loom the moment evidence suggests the virus has broken containment lines.

Genetic sequencing and the discovery of a potential “missing link” offer increased confidence in running down Victoria’s latest COVID-19 cluster sooner rather than later.

However, the emergence of an additional four new cases on Tuesday afternoon is a sobering reminder of just how quickly the cluster could grow into a wider outbreak if contact tracers cannot use the new leads to quickly contain its spread.

That is, if it has not spread already.

People queue at a Covid-19 testing station in Melbourne.

Genetic sequencing confirming the new Whittlesea outbreak stems from the return of a known case from South Australian hotel quarantine on May 4 is a massive relief.

It assures health authorities they are not dealing with a completely new outbreak that had been spreading undetected.

Discovering a fifth positive case overnight on Monday was also a huge help to investigators. Because the man in his 60s was symptomatic before the other Whittlesea cases he becomes at least part of the missing link connecting them to the South Australian case.

With the links now much firmer, contact tracers can begin building containment lines around everyone remotely close to the chain of transmission since May 4.

Establishing firm links has also saved Melbourne from another lockdown, at least for now.

But the scale of the containment task became crystal clear when four members of the man’s family also tested positive to COVID-19.

It underlines the presumption the man has been infectious long enough to pass on the virus while circulating since May 15.

It also raises the number of cases in the Whittlesea cluster to nine – and that’s nine different avenues in which COVID-19 may have already spread.

It’s almost certain cases will grow over the coming days. If they remain within the Whittlesea containment lines mask-wearing and gathering limits may be enough to wait out the cluster.

But the moment there is evidence suggesting the virus has already spread lockdowns are likely to loom over Melbourne again.