Grant McArthur: The factors that could make or break seven-day lockdown

Given past experience Victorians are right to be worried about lockdown being extended, but these factors mean we could be released earlier.

The number and size of exposure sites will be more crucial in deciding whether Victoria’s lockdown ends after seven days than the simple number of new cases each day.

With more than 10,000 primary or secondary close contacts already identified it is expected there will be an increase – probably a significant increase – in COVID-19 cases over the coming days.

But as long as those cases remain among the close contacts already isolated and linked to the Whittlesea cluster’s current 26 cases, then authorities can be confident contact tracers have reined in its spread.

What will concern them much more is if the list of exposure sites continues to multiply, having already jumped from a handful to an unmanageable 100+ in three days.

It is expected – or at least hoped – that most of the 10,000 contacts have been moving in the same circles as each other and those already confirmed as cases. This means that even when some test positive the number of exposure sites where COVID-19 can escape should not significantly grow.

The number of exposure sites will be crucial in deciding whether Victoria’s lockdown ends after seven days.

However, if new cases lead to more and more exposure sites emerging into mid next week Victoria will be in a situation where no amount of contact tracing can get ahead of coronavirus’ spread.

If that happens, or if even a few positive cases emerge without links to existing cases, then seven days may just be the beginning of restrictions.

Melburnians will already be fearing any extension. An initial a four-week lockdown in 10 postcodes last June grew to a six-week lockdown across the entire city in July, then an agonising shutdown stretching 111 days.

Back then Premier Daniel Andrews set a target of dropping below five daily cases before stage-four restrictions could ease – but that was long after the virus had jumped all containment lines, so the same simple number requirement should not determine the end of the current “circuit-breaker”.

Victorian Chief Health Officer Brett Sutton may recommend the state stay in lockdown if the cluster cannot be controlled.

A review of that marathon lockdown by Monash University offers further hope of avoiding an extension beyond next week.

They found the second-wave lockdown could have been cut in half and with less severe restrictions if health authorities pushed the government to act 10 days sooner, rather than waiting until July 9 when 143 new cases were recorded.

This time they have jumped to a lockdown after just 26 cases, so it seems the health department and government have all listened.