Professor Peter Collignon of the Australian National University said three days was not long enough because it normally takes an infected person five days to show symptoms after catching the disease.
‘Three days will not solve the problem because the average incubation period is five days,’ he told 2GB radio on Monday morning.
Brisbane’s three-day lockdown won’t prevent the highly infectious UK strain of Covid-19 from spreading around the community, a disease expert has warned. Pictured: Brisbane on Sunday
Scientists say it can take up to two weeks for an infected person to get symptoms, meaning cases can appear 14 days after a transmission event.
‘You really have to wait, people have to isolate for 10 to 14 days, even 28 days for two full incubation periods,’ Professor Collignon explained.
But instead of arguing for a longer lockdown, the disease expert said it was ‘unreasonable’ to contain 2.5million people in their homes over one coronavirus case.
‘This is a single case, and I don’t think anyone in the world has ever done this before,’ he said of the three-day lockdown introduced on Friday.
‘It almost says we don’t have faith in our contact tracing system.’
Professor Collignon said New South Wales has done a good job of managing outbreaks with contact tracing rather than city-wide lockdowns and cautioned premiers against following an elimination strategy.
‘The trouble I have with elimination is that people become complacent… It’s inevitable we will have leaks,’ he said.
‘That is the reality, we just need to make the probability lower, but you have to accept you might get it.
Queensland recorded zero local cases on Saturday and Sunday during lockdown
‘I don’t think it’s reasonable that every time we get a case we lock down our cities.’
The Greater Brisbane region was put in lockdown from Friday until 6pm on Monday after its was confirmed that a hotel quarantine cleaner had caught the highly contagious UK strain of Covid-19.
She was out and about for five days, taking trains and buses, before testing positive and going into isolation.
Prime Minister Scott Morrison said he supported the three-day lockdown to buy contact tracers time to get in touch with all of the cleaner’s contacts.
Professor Raina MacIntyre of UNSW said the lockdown was the right decision.
‘I think they did do the right thing in reacting quickly bringing in the mask mandate and doing a sharp, short lockdown,’ she told ABC News on Monday morning.
But she, too, warned that cases may appear two weeks after transmission.
‘Really you need to watch the incubation period from the last possible exposures from that index case,’ she said.
‘So when two weeks has passed after the last possible exposures – and there’s still no cases – then you can relax.’
Queensland recorded zero local cases on Saturday and Sunday.
‘Let’s see what our numbers are tomorrow (Monday), and then we will update Queensland about what the proposed steps forward are following on from that,’ Premier Annastacia Palaszczuk told reporters on Sunday.
Victoria has recorded zero new local cases of Covid-19 on Monday, for the fifth day in a row. There was one new case in hotel quarantine.
Queensland made masks mandatory for the three-day lockdown from Friday to Monday