A fit and active 65-year-old, Glenda Shulman used to run up hills near her home, yet four months after contracting COVID-19 she struggles to make it up the slightest incline.
She was on the ill-fated Ruby Princess cruise in March with six friends from Wollongong when she came down with the virus halfway through the voyage.
She would experience perhaps the mildest case of the virus among the group - with three of her party needing to be hospitalised, including one who spent five weeks on a ventilator in Wollongong Hospital.
Yet the long term effects of the virus are the big unknown - and Ms Shulman is this week undergoing tests to find out why she's still suffering severe fatigue and breathlessness.
"On day five of the cruise I woke up with a cough - I didn't think about coronavirus at the time, I thought it was a chill from leaving the balcony door open," she said.
"Then I started to get a bit of a scratchy throat, and just felt very tired - instead of going for drinks and to watch a show after dinner, I'd be going back to my room to sleep."
Ms Shulman, who lives in Brisbane, said another member of their party - Henry Karpik - fell seriously ill onboard and a test after their return on March 19 confirmed he had COVID-19.
Even still, Queensland Health refused to test her - as she didn't have all the symptoms of the virus, including a fever.
"It was early days then to be fair, so not everyone was being tested," she said. "So my GP organised a test through a private pathology company and the next day I received a call to say I was positive.
"But while the cough and scratchy throat are long gone, I've still got shortness of breath - I can't seem to get a full breath in.
While the cough and scratchy throat are long gone, I've still got shortness of breath - I can't seem to get a full breath in.Glenda Shulman
"I'm usually a very fit person - I used to cycle 30km three times a week and went on 100km organised rides. I used to run up the hill, now if I go for a walk and go up a slight hill, I'm puffed.
"I've got a lack of feeling in my hands and I'm just so tired."
Post-viral fatigue can be one of the long-term effects of the virus, according to Illawarra Shoalhaven Local Health District's Head of Infectious Diseases Spiros Miyakis.
"We have to remember that COVID-19 has only been around for eight to nine months to our knowledge, so we are learning more about it all the time," he said.
"We do know that a certain percentage of patients experience prolonged fatigue after that viral phase goes away. It's called post-infectious disease syndrome, and it also witnessed in other infectious diseases.
"Invariably that fatigue does go away, but it may take people several weeks to recover."
The Associate Professor at University of Wollongong's School of Medicine said those with more severe cases of COVID-19, especially those who'd spent time in intensive care and on ventilators, may experience more serious long-term effects.
That included lasting damage to major organs such as the heart and lungs, and even long-term neurological complications.
For Ms Shulman, and her cruising companions, it's a concern.
That includes Mr Karpik, a former Wollongong detective, who was critically ill and is now undergoing extensive rehabilitation after several weeks on a ventilator.
Another member of the party - Bill Wright - suffered a heart attack after he 'recovered' from the virus - although does not believe it was related to COVID.
He and his wife Lucia both had very different symptoms while infected - he had a "slight cough and runny nose" while she had fever, vomiting and diarrhoea.
"My symptoms started the morning I got off the ship," he said. "But my symptoms were very mild - I've had worse flus - and were gone within a week.
"Lucia's symptoms lasted for a similar time and we've had no lasting symptoms."
It's the array of symptoms - and severity of the illness - that means it's vital anyone with any symptoms get tested, A/Prof Miyakis said.
"In the first week we know that most people initially report symptoms of upper respiratory infection - flu-like symptoms including cough, fever, shortness of breath, joint pain and headaches," he said.
"Other symptoms may include an alteration in taste and smell; or gastrointestinal symptoms such as diarrhoea, nausea and vomiting. Sometimes gastrointestinal symptoms predominate, rather than respiratory."
It was during the second week though that the virus could really take hold.
"From days 10 to 14, some people may go on to develop more aggressive symptoms, which can be unpredictable," A/Prof Miyakis said.
"These more rare symptoms may include fulminant pneumonia, rashes and swollen fingers and toes, stroke or blood clots elsewhere in the body, as the body's immune system overreacts to contain the virus and the disease takes over.
"It can lead to a whole range of manifestations in all organs - which can cause multi-organ failure, and ultimately death."
A/Prof Miyakis urged people to take preventative measures - including social distancing and mask-wearing in areas where social distancing cannot be observed - and to pay particular attention to hand sanitisation, cough etiquette and personal hygiene measures.
"This virus is very easily transmitted - more so than many other viruses" he said.
"Unfortunately it's also a multi-systemic disease, which may have long-lasting effects for some."
A/Prof Miyakis said these measures were our only defence until there was a vaccine, effective treatment or the virus dying off by itself.
"We don't know what the pattern of COVID-19 will be - any mutation could make the virus transmit easier and become stronger, or hopefully it might even perish by itself if it doesn't find the right mutations," he said.
"We can't just wait for a vaccine or treatment, we can't count on it dying off by itself. We don't want to pay the toll of herd immunity - which would be a huge loss of lives.
"The situation currently is in our hands, if everyone takes protective measures - including adherence to hand hygiene and complying with social distancing and public health advice.
"Getting tested and self-isolating with even minor suggestive symptoms or after visiting places at times when transmission might have occurred, as advised by the authorities, is of paramount importance."
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