Sydney's 'mother of all superspreaders'
An infectious diseases expert has warned there could be 3000 new coronavirus cases in NSW by early January, and Christmas could be cancelled unless a short lockdown is introduced in Greater Sydney.
Infectious diseases expert Professor Raina MacIntyre of the University of NSW has warned that Christmas Day and New Year's Eve are superspreading events that could see current coronavirus cases quickly blow out, leading to more than 1000 people being infected at end-of-year celebrations.
NSW on Sunday recorded 30 new coronavirus cases in the past 24 hours, with 28 of them linked to the Avalon coronavirus cluster. There have now been a total of 68 cases associated with the cluster.
The #COVID19 outbreak in #Sydney, timing, peak infectiousness, #epidemic growth and why New Years Eve may be the mother of all super-spreading events #COVID19nsw #NewYearsEve #Christmas2020 https://t.co/1xDqk48EE6 pic.twitter.com/MUkvpQz5qA— Global Biosecurity (@Globalbiosec) December 19, 2020
Prof MacIntyre said the exponential nature of the coronavirus could see cases grow to 120 by Christmas Day and these people could infect another 300 to 400 people at family gatherings.
This has even more serious implications for NYE celebrations, which are only six days after Christmas.
She said about 90 per cent of people became infectious by day five of getting the coronavirus and anyone infected at Christmas lunch would likely be at the peak of their infectiousness when they attended 2021 parties. This could see a further 1000 people infected.
"This is why this outbreak is different because we've got two superspreading events ahead of us and people will be maximally infectious on NYE - that's why it's such a dangerous situation," Prof MacIntyre told news.com.au.
"We could be looking at potentially 3000 cases by the second week of January."
Prof MacIntyre said the situation means authorities need to act now.
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"I think the problem is there is very little time left, these two events (Christmas Day and New Year's Eve) are going to happen, they are fixed dates," she said.
If cases numbers on Monday are higher than today's, Prof MacIntyre believes a short, sharp lockdown of Greater Sydney is the best option to "salvage Christmas".
"If we see 100 cases on Thursday we are going to have to cancel Christmas," she said.
"We may also be forced to abandon all plans for New Year's Eve if we take a softly, softly approach.
"Last year on New Year's Eve we were watching the bushfires unfold and we really don't want another disaster."
While it's possible the current restrictions would be enough to drive down case numbers, Prof MacIntyre believes authorities cannot afford to wait and see.
"It's possible that everything could be controlled with the measures they've used but it's not like at any other time of the year, there are unique and different risks at this time of the year," she said.
"The difference with the Crossroads outbreak is that we had no way of predicting whether there would be any superspreading events where the virus would get out of control, in this case we have 100 per cent certainty that there will be two superspreading events: December 25 and December 31."
She said the longer authorities waited to act, the harder it would be to control the spread.
Most of the cases so far have been located in the northern beaches and authorities have already told residents in the area not to leave their homes but Prof MacIntyre believes the stay-at-home orders should be extended to Greater Sydney.
"If the virus has spread to other parts of Sydney we may not be aware of it for another week or so and by that time it will be too late," she said.
"We have to assume a worst case scenario and stamp it out to ensure a safer Christmas Day and New Year's Eve."
Prof MacIntyre is one of a number of experts who believe NSW authorities should be bringing in stricter restrictions.
On Friday, Melbourne University epidemiologist Professor Tony Blakely told news.com.au that Sydney's northern beaches should have been in lockdown rather than being subject to soft stay-at-home orders. Authorities did subsequently introduce stronger restrictions giving residents just four reasons they were allowed to leave home. Those in the Greater Sydney region have also been restricted to a maximum of 10 visitors in their homes.
Prof Blakely also suggested that masks should be made mandatory for all residents in Greater Sydney and Prof MacIntyre said any measures like this would make a difference.
"Making masks mandatory will definitely help as there are people hitting the shops in record numbers," she said.
"If you don't mandate masks you only get about 30 per cent of people doing it, which is not as good as 100 per cent.
"I think they need to look at the seriousness of the timing and what we know about peak infectiousness."
Originally published as NYE could see 1000 people infected