Number proves lockdowns can’t beat Delta

NSW Premier Gladys Berejiklian has been pummelled for locking down late. But one number suggests an early lockdown would have made no difference.

NSW Premier Gladys Berejiklian has been pummelled for locking down the state too late.

At Monday’s press conference, she was again forced to defend her handling of the pandemic — specifically the speed of locking down all of Sydney.

Greater Sydney went into lockdown on June 26, 10 days after the outbreak first began and two days after the government knew it had failed to contain the spread from a birthday party in West Hoxton in the city’s west.

Several reporters fired off questions about the lockdown decision and Ms Berejiklian responded by defending her health team.

“(You can) criticise government, but our public health officials are the best in the land,” she said.

The June 24 realisation was five days after the event took place and three days after the department had first began tracing people who were there.

NSW Premier Gladys Berejiklian. Picture: Brendon Thorne/Getty Images

Chief health officer Kerry Chant has previously said her team underestimated the spread from the West Hoxton party.

“With the benefit of hindsight, I think it’s easy to say there was a greater risk of a seeding event in southwestern Sydney than was appreciated at the time it emerged,” she said.

The outbreak, which has since overwhelmed contact tracers, is the biggest in Australia since the pandemic began.

But it has been followed by another huge outbreak in Melbourne that Victorian Premier Daniel Andrews has admitted is the end of the state’s pursuit of zero cases and a lockdown in the ACT after the nation’s capital went a year without a single case.

All three lockdowns are different but they pose one important, central question: Do lockdowns no longer work against more infectious strains of coronavirus?

States end pursuit of Covid zero

The number that could prove lockdowns can’t beat Delta is one.

That is the number of cases the ACT had when it was thrust into a snap seven-day lockdown on August 12.

The case was the first for Canberra in more than a year and involved one individual who was infectious while in the community.

Previous iterations of the virus that arrived in Australia could be defeated by a short-sharp lockdown at such an early stage in the outbreak. You only need to look at what Queensland, South Australia, Tasmania and the Northern Territory managed to do to defeat Covid-19 when it threatened outbreaks there.

But the lockdown in the ACT goes on, more than a month after it started.

On Monday, there were 13 new local cases. Of those, 10 were infectious in the community for some time, authorities said.

There are now 285 cases linked to the outbreak despite a super aggressive lockdown.

BTW if ACT doesn't get this to zero off a day 1 single case lockdown, you can probably just ditch the idea of anyone doing it reliably.

This place has every social, economic and industry structure advantage to make aggressive lockdown more likely to work.

— arwon (@arwon) August 24, 2021

In Melbourne, Delta also changed the game.

On August 3, Victorians were celebrating an achievement no jurisdiction anywhere in the world had come close to — beating back a surge in new cases linked to the highly infectious variant out of India.

It was the first day of zero new local cases since Delta first arrived on July 12. But it would not last.

The next day a teacher from Al-Taqwa College in Truganina — a school that has endured more than its fair share of the Covid burden — became infected.

Two days later Victoria was back in lockdown. This time there was no coming out.

It took just over a month to go from zero new cases in August to Monday’s daily tally of 473.

The speed and ferocity with which the Delta strain moves around the community has flipped Australia’s virus story on its head.

It’s why piling on the NSW Premier for failing to act sooner might be pointless. We genuinely don’t know whether acting earlier would have made a difference.

Ms Berejiklian has outlined a road map out of the current statewide lockdown. Picture: Brendon Thorne/Getty Images

‘It’s not that simple’

A study of lockdown effectiveness, one frequently cited in relation to the NSW outbreak, says that if you wait three days to lock down it extends the lockdown for three weeks.

Epidemiologist Catherine Bennett says the University of Sydney study from November last year, which was published in the journal Nature, lacks nuance.

Writing for The Conversation, the Deakin University Chair of Epidemiology said “whenever we’re evaluating a lockdown, there’s always an element of hindsight being 20/20”.

“During this pandemic we’re often making decisions in situations of considerable uncertainty,” she wrote.

“It’s easy to sit here and say locking down earlier would have made a difference. But when should it have been called? When we knew of only ten cases?

“While infections among casual contacts were concerning, nobody knew 24 future cases would soon be exposed to a case at private party of 30 held later that same night.”

She said she does not think “you could defend … epidemiologically” going into lockdown when there were just 10 cases.

As we now know, the 10 cases were the tip of the iceberg. They climbed to 25 two days later, 54 two days after that and 112 two days after that.