Deadly coronavirus is rapidly spreading in a terrifying new way and health bosses have no idea where it is coming from.
The number of community transmission cases with an unknown source has tripled in NSW from 46 on Sunday to 145 on Friday, and doubled from 88 on Thursday.
Most cases in NSW have come from overseas or have been transmitted to a person by someone known to them.
Community transmission is where someone becomes ill and authorities can’t trace it back to a known case, meaning the virus is uncontrollably spreading.
The huge spike in cases where the source of the infection was unknown prompted a warning from NSW Premier Gladys Berejiklian.
‘The one figure that we are most worried about is the number of people that are getting it within the community,’ she said on Friday morning.
‘That’s why it is so important that all of us maintain social distancing if we have to be out and about.
‘And in the case of my parents, I haven’t let them out of the home and I won’t.’
She said people who caught coronavirus through an unknown source were also less likely to suspect they were infected and know they needed to self-isolate.
Victoria’s Health Department said on Friday this worrying trend may also be starting there as its community transmission cases jumped from nine to 16 overnight.
Other states have confirmed a handful of such cases in recent days and have their own fears they could balloon in coming days.
Until this week, Australia’s coronavirus cases were almost entirely travellers returning from overseas, and those they came in contact with.
However, community transmission means COVID-19 is spreading among people who haven’t been in contact with either – making the virus virtually untraceable.
Health authorities are desperate to keep a lid on community transmission as it is by far the greatest threat to Australia’s ability to handle the pandemic.
Ms Berejiklian said an increasing number of community transmissions would likely lead to stronger lockdowns.
‘When it is community-to-community transmission and you don’t have a source, that means the virus is starting to spread in the community without us knowing where and that’s a concern,’ she said.
‘We are starting to see an increase in the spread from unknown sources and that’s why we are stepping up the compliance, we are stepping up the advice.’
The Australian Health Protection Principal Committee, which advises Prime Minister Scott Morrison, said a 50 per cent community transmission rate was an important threshold.
On Thursday the committee said Australia was approaching that proportion and that was why the stage 2 lockdown was implemented on Wednesday.
It said the ‘major trigger’ was ‘the rapid growth in total cases and the case-load particularly in Sydney, Melbourne and Brisbane/Gold Coast.’
The number of community transmission cases would determine when stricter lockdowns would come in as Australia tries to ‘stay ahead of the curve’.
‘A trigger for local lockdown provisions in a part (or parts) of the country (as seen in Italy and elsewhere) would be a substantial growth in locally transmitted cases,’ it said.
‘Which could be predicted to exceed the future capacity of the region’s health services.’