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Should Australia be testing more broadly for the coronavirus?

Doug Hendrie 3/03/2020 4:40:21 PM The new coronavirus can hide amid a sea of common cold and flu symptoms. One virologist argues we should consider wider exploratory testing.

Broader coronavirus testing would be expensive – but would it find the virus?

‘Looking at epidemiological data is like looking at the light from a far-away star. You are always seeing the past. This is what we have seen in Iran, Italy and now in Washington State [in the US].



The virus was introduced, it spread for a few weeks and when enough people were infected for serious cases to pop up, they were discovered and slowly the rest of the iceberg came into view as testing expanded.’



That is molecular biologist and science journalist Kai Kupferschmidt, posing the question on Twitter: Why are countries not testing more broadly for the new coronavirus, COVID-19?



It is a question that resonates with University of Queensland virologist Associate Professor Ian Mackay.



To get ahead of the virus, Associate Professor Mackay has called for exploratory community testing to see if it is already circulating under the radar among people with mild symptoms.



The challenge is separating signal from noise, given the significant crossover of symptoms with influenza and with other coronaviruses that cause the common cold. Around 80% of COVID-19 cases only experience mild symptoms.



‘It’s now apparent there is a spectrum of disease, with mild outcomes blending in with normal cold and flu seasons. We need to be testing,’ Associate Professor Mackay told newsGP.



‘Do we want to be caught by surprise or to get on the front foot?



‘There is a lot of noise, which is even louder right now because we’ve had a large start to the year in terms of flu numbers. Lab testing is the only way to tease [flu and coronavirus] apart.’



‘Based on what we’ve seen in the US, more testing is a good idea. It’s in many countries now that we have lots of travel from … and quite a few infected are travelling.’



The virologist’s calls come after gene sequencing analysis by US computational biologist Dr Trevor Bedford indicated that coronavirus had been spreading undetected in Washington State for weeks.



On Twitter, Dr Bedford said the fact two people who had not had contact were infected six weeks apart indicates cryptic transmission has been occurring.



‘If the US is seeing cryptic transmission, we could [be] as well. Testing is an expensive process, but we need to do it,’ Associate Professor Mackay said.



‘We know the virus is present before people are symptomatic and we don’t know how long they shed for.



‘This virus is different from the first SARS, which seemed to shed only when people were more ill. It blends in, with coughs and colds that we all suffer from.’



University of New South Wales (UNSW) Professor of Global Biosecurity Raina MacIntyre told newsGP that accumulated evidence now shows there is ‘substantial potential’ for asymptomatic transmission of COVID-19.



‘In the early days we assumed it was like SARS, and only contagious in people with symptoms. We now know that anyone at risk – a contact of a case, or an evacuee from a high risk zone – should be tested,’ she said.



‘The evidence also suggests repeat testing may be required, especially if relying on a throat swab, which seems the most likely to yield a false negative result. A nasal swab is more sensitive, a sputum even more so, and toward the end of the illness, an anal swab may remain positive longer than a throat swab.’



Professor MacIntyre believes the response to the virus has been held back by a lack of serological testing.



‘[S]erological testing … will help greatly in identifying people who have been exposed more definitively,’ she said. ‘Whilst a positive serology may not indicate active infection, a negative throat swab cannot rule it out.



‘At least with serology we can determine if someone has been infected. Hopefully serology will be available soon.’



Most Australian states are still conducting testing as needed. If a suspected case is found, the state health department will undertake contact tracing and testing as required, while possible cases who self-identify based on travel history are tested at general practices or in emergency departments.



Since 6 February, South Australian GPs have been able to test people with flu-like symptoms for both the novel coronavirus and the flu.



‘Novel coronavirus testing will become part of routine respiratory infection testing, resulting in a more efficient and streamlined process for GPs,’ SA Health said in a statement at the time.



‘While it will result in more South Australians being tested, it will mean more people will be able to rule out any links to novel coronavirus.’



South Australia has had three cases of the virus, with all three fully recovered.



Other states have not yet followed suit.



Victoria’s Chief Health Officer Adjunct Clinical Professor Brett Sutton told newsGP that testing is ‘effectively wider scale’ already, given the widening of national case definitions to include all top areas of transmission globally.



‘We give all practitioners scope to test anyone who’s travelled internationally. When we pick up positives from those, we should consider casting further,’ he said.



But he said it is not time to test any Victorian with coughs and colds due to the danger of losing focus on the highest risk.



‘We also need national accreditation and approval on commercial tests that can roll out to all primary labs. [We’re] not there yet, so we’re using our reference lab here in Victoria. It has more than enough capacity for current demand,’ Professor Sutton said.



Associate Professor Mackay stresses that, to date, there are no clinical signs the virus is spreading actively in the community.



‘Wider testing now is mostly to gauge whether more of the virus is occurring or not. This is an exploratory and science-based enquiry. It probably isn’t happening,’ he said.



That thinking is borne out by Australia’s Chief Medical Officer Professor Brendan Murphy, who said at a press conference on Tuesday that there is not yet any evidence of sustained community transmission.



One challenge of mass testing is the high cost for a potentially very low or non-existent result, as Associate Professor Mackay points out.



Despite seemingly widespread community transmission in China’s heavily populated southern province of Guangdong, more than 320,000 tests of influenza-like illness only found 448 cases (0.14%), based on the recent report from the World Health Organization–China joint mission on coronavirus.



Around 10,000 people have been tested for coronavirus in Australia, with 35 confirmed cases. Fifteen of those have now recovered.



The RACGP has more information on coronavirus available on its website.



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