The growing number of people with coronavirus where their point of infection can’t be traced in Australia is a worrying statistic amid the nation’s fight against the virus, a leading virologist has warned.
On Friday, the number of cases where the source wasn’t known rose to 336 in NSW, by far the worst-hit state across the nation.
Those cases made up 14.1 per cent of all cases in NSW, up from Thursday at 13.4 per cent (307 untraced cases) and nearly double of the 7.2 per cent of cases eight days ago when there were 88 untraced cases in the state.
That steady increase is in contrast to the overall number of cases in NSW, with the daily increase decreasing over the last three days.
On Friday morning, NSW Premier Gladys Berejiklian expressed her concern over the rising number of cases without a source, suggesting while the state may appear to have slowed the daily increase of cases, there was more work to be done.
“What concerns us greatly is the number of cases being acquired without us knowing the source,” she said.
“That is something we have to keep mindful of and something that our health experts are most worried about.”
Professor Ian Mackay, a virologist at the University of Queensland, told Yahoo News Australia now that the number of cases being imported from overseas were quickly diminishing following a travel ban, it was now clear to see the threat local transmission poses.
“It shows we’re not just getting cases from travellers, where we were getting most of our cases from for a long time, and it’s been a little bit hard to keep track of the differences,” he said.
“Each day we hear about the numbers but we don’t necessarily hear what percentage are from local spread.
“When these numbers in the community do increase and they’re not linked to travel then we’ve obviously got ongoing spread developing in the community and it’s really important we try and slow that down as much as possible.”
Ms Berejiklian said it was imperative for the people of NSW to continue to abide by the strict social distancing regulations implemented on Monday to prevent further unknown community transmission.
“We have to maintain our vigilance, that's why all of us have to keep sticking to the rules and all of us shouldn't leave the home unless it's for the specific reasons [the NSW government] outlined earlier.”
Prof Mackay agreed, suggesting if the current social distance restrictions could be upheld and adhered to, the nation should hopefully be able to stop the the number of transmissions spiralling out of control.
Under current restrictions, gatherings of more than two are prohibited while people are only allowed to leave their households for either essential work, education, essential shopping and exercise.
Asymptomatic cases increasing unknown spread
Recent research has suggested up to 50 per cent of coronavirus cases are asymptomatic, with Prof Mackay identifying those without any symptoms as “a risk”, adding it will be “hard to trace all of them”.
“It looks like that’s where we’ll be seeing some of our community spread coming from, how much we don’t really know, it might be a tiny little bit or it might be a whole lot, but the cryptic spread is definitely a risk.”
Such spread, which has caused cases in the US to rocket beyond 200,000, has prompted the widespread use of masks within the community.
Prof Mackay said while for a long time Australia’s testing criteria didn’t allow for someone without known contact or without symptoms, he said hopefully a widening of test availability for those who aren’t showing symptoms would help contain the spread.
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Prof Mackay advised any contacts of known cases even if they are not sick to be tested, if sufficient tests were available.
Prof Mackay said one of the biggest issues in regards to spread was when someone contracts the virus unknowingly before passing it on to their family due to close contact.
But he praised the efforts of the state governments and their rigorous contact tracing efforts.
Such action across the nation has enabled “a much slower spread of a virus within our community” and gives the nation time to prepare for when there is an increase in severely ill patients who will need ICU beds, Prof Mackay said, and in turn will buy Australia time.
“Getting a vaccine or having some anti-virals that can treat or prevent illness is really the end game we’re aiming for here to give people immunity without having to go through the disease and possibly become very sick or die,” he said.
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