Infectious disease physician Sanjaya Senanayake said clotting was now one of the main mysteries facing doctors treating COVID-19,though the cases were still low and mostly among severe patients. In Australia,where total infections are relatively few,health authorities say they are yet to see patients suffering from strokes or clotting.
"There does seem to be an association with COVID-19,"Associate Professor Senanayake said.'We don't know why yet. It's probably a disruption to the clotting mechanism of the blood vessels caused by inflammation ... when the body's immune response kicks in."
That same,overzealous immune response is often responsible for much of the damage caused by a new pathogen – as the body's war on the virus claims healthy cells in the fallout. The other two dangerous coronaviruses to emerge in the modern era,SARS and MERS,also led to some clotting and stroke,though there was"not a strong association",Associate Professor Senanayake said.
This virus uses the same ACE2 receptor to hack into human cells as SARS,and it is thought to be even better at it,making it more infectious.
"ACE2 is found a lot in the lungs,which is why[COVID-19] gives people pneumonia,"Dr Oxley said."But if you follow ACE2 around the body,it explains why the virus is attacking other[organs such as] the heart. ACE2 is also found on the walls of blood vessels,so our working theory is that it attacks the vessels and starts an inflammation cascade."
Clotting could also be behind growing reports of heart failure in some COVID-19 patients. But Associate Professor Senanayake said clots could be caused by the virus infecting the heart or something"non-COVID-specific"altogether,more in line with what you would already expect from an intense infection.
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Australia’s Deputy Chief Medical Officer,Nick Coatsworth,suggested last week that clots could form in the legs and travel to the lungs in those unwell with sepsis[or] lying in intensive care for a long period. The cause of COVID-19 clotting was still unclear,he said,but Australia was watching cases overseas closely to guide treatment.
Associate Professor Senanayake said advice to consider blood thinners in COVID-19 treatment had already been put out to doctors internationally. At Dr Oxley's hospital,Mount Sinai,internal guidelines had been updated overnight,instructing staff to put all COVID-19 patients entering intensive care on powerful blood thinners.
"There's been more clotting issues beyond just this[stroke cluster,"Dr Oxley said."This is not like anything we've seen before,we need to find out more but it's not just a usual infection.
"We're also worried people are missing the early signs of stroke because they're afraid to go to hospital."
For Dix,in hospital isolation this month with a monster clot slowly breaking apart in her lungs,it hurt to breathe,but she still found herself snatching moments to sing – even fielding requests from a patient next door.
"Every day I practised my breathing exercises,to help test how I was doing,"she said.
Having long kept a strict health and hygiene routine to stay well for performances,Dix now laughs that the world has"turned into opera singers"to avoid catching COVID-19.
"Still some people's attitudes amaze me.[They] think they'll be fine because they're young and healthy. None of us are immune.
"[My voice] still isn't[healed] but I'm so lucky to be here. I know it will come back."
If you suspect you or a family member has coronavirus you should call (not visit) your GP or ring the national Coronavirus Health Information Hotline on 1800 020 080. If you are experiencing serious symptoms,such as difficulty breathing,call 000.
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