As the coronavirus outbreak in the US continues to spiral out of control, it is feared the exponential growth in cases is being fuelled by those infected who are displaying no symptoms at all.
The US has 203,608 confirmed cases of COVID-19 as of Thursday morning (AEDT), with a growing number of cases asymptomatic.
Director of the Centres for Disease Control and Prevention (CDC) Dr Robert Redfield believes up to a quarter of those infected have the ability to spread the virus without realising they have it.
"Information that we have pretty much confirmed now is that a significant number of individuals that are infected actually remain asymptomatic. That may be as many as 25 per cent,” he told National Public Radio.
However, alarming research from Iceland suggests that figure could be as high as 50 per cent.
While the WHO and CDC have routinely said the general public should not be wearing masks, there is suggestion they may be beneficial with the potential that large sections of the population are infected without any knowledge of it.
Director of the National Institute of Allergy and Infectious Diseases Dr Anthony Fauci said if there were sufficient stockpiles to ensure the supply to frontline medics, there may be some benefit to advising the use of masks.
Yet infectious disease expert Dr Mike Ryan, who is leading WHO’s response to COVID-19, said on Monday there was no evidence to suggest masks provided any benefit and could actually hamper the efforts to prevent the spread.
In Australia, there is no need to wear masks in public for those people showing no symptoms, Associate Professor Ben Mullins at Curtin University’s School of Public Health said.
“The face masks people are wearing are not giving many benefits other than maybe stopping them from touching their face and there may be some benefit if someone coughed right next to you, but you shouldn’t be getting close enough to people for that to happen,” he told Yahoo News Australia.
However, Prof Mullins said the widespread use of masks, which has been a requirement in China, can offer some benefit when there is a lack of social distancing and there are large numbers of unidentified cases.
“The one benefit of when you do let people out and you’re having trouble maintaining the social distancing then wearing something like this will stop any remaining infected people you haven’t tracked down and isolated [infecting others].”
UNSW infectious disease expert Professor Raina MacIntyre said Australia must ramp up its testing to ensure asymptomatic cases are detected.
“We don’t have data on silent transmission that could be bubbling under the surface when infected people don’t have any symptoms or have very mild illness,” she explained.
“We should be testing people without symptoms who fall into the groups outlined in the current Australian guidelines, so that we do not miss asymptomatic cases in high risk groups.”
Prof MacIntyre said asymptomatic cases has likely “driven the silent growth” of the pandemic in the US, and similarly to Spain and Italy, its health system is now struggling to cope with the influx in patients.
She pointed towards Japan and South Korea, who tested high risk people without any symptoms, who have both been able to flatten the curve after initial substantial outbreaks.
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