What does COVID-19 do to the body and what's it like to have the illness?
Sherryn Groch
The Age
March 13, 2020
A cough, a clammy forehead, shadows on the lungs. Most people infected in the viral pandemic now sweeping the globe will come down with only a mild case of the mystery illness. Some won’t know they’ve had it at all. But when it's bad, it can mount an attack on the whole body – and start a storm in the lungs.
How it plays out depends on the two factors important to any invasion: the strength of your defences and the strength (or dose) of what you’ve been hit with.
Connor Reed, 25, knows well the racking cough and spiking fever of the illness now called COVID-19. He says he came down with it late last year in the centre of the initial outbreak, Wuhan in China. He still lives just a 20-minute walk from the wet market where it's believed the strain jumped from wild animals into humans.
At first, Reed seemed to just have a cold. A week on, then early December, he was already feeling better when a fever hit, and a cough. His whole body started to ache. Another week went by. He thought he was on the mend until the cough became deeper, seeming to settle at the bottom of his lungs.
"It was hard to breathe," Reed says. "Even walking to the bathroom, I felt like I was running out of air. My ears hurt from it, I lost my balance at times. It started to get scary, like the worst flu I've ever had."
Reed ended up in hospital and, after a full day of testing, he says doctors told him he had a "new kind of pneumonia". Fortunately, he was fit and healthy: his life didn't appear to be in danger. Steroid inhalers helped reduce inflammation in his lungs and, more than a month after that first sniffle, Reed recovered. When he called the hospital in early January to ask more about his test results, they told him what was about to hit headlines around the world in just a matter of days – a new kind of coronavirus had been identified in humans. Reed was one of the earliest suspected cases.
Three months on, what do we now know about COVID-19 and how the body reacts? What is treatment like? And how long does recovery take?
How does the coronavirus infect a person?
You can’t see the virus with the naked eye – it’s nanometres wide. But when someone is infected, they can shed it, shooting viral particles at least a metre into the air in water droplets from their nose and mouth, usually through coughing or sneezing. Viruses infect a new host by harnessing our own cellular machinery to replicate. To get in, they need the key – a receptor within a cell they can bind to. Which cell a virus latches onto largely determines where it will spread throughout the body – and helps guide treatment.
The four main coronaviruses found in humans tend to colonise only the nose and throat. Collectively, they cause about one in four cases of the common cold and symptoms are mild: a runny nose, a sore throat, sometimes a cough or a fever. But since 2003, three dangerous coronavirus illnesses have emerged in humans: SARS (Severe Acute Respiratory Syndrome), which also spawned global panic when it exploded onto the scene 20 years ago, the more deadly but less common MERS (Middle East Respiratory Syndrome) and now the latest, COVID-19, which has already infected more than 135,000 people and killed close to 5000.
All three attack the lungs as well as the sinuses, sometimes developing into viral pneumonia – and, because they're new, there's little natural immunity to fight them off. COVID-19 is about 75 per cent similar to the SARS strain, and even thought to bind to the same cell receptors (ACE2), which are largely found in the lungs.
Early studies suggest this virus might be better at hacking into that receptor than SARS, which is why it's more infectious, says Professor Sharon Lewin, director of the Peter Doherty Institute for Infection and Immunity. A spokesman for the Australian Department of Health offered a different theory: the new virus appears to be replicating fastest in the nose and throat, rather than the lungs. That could make it more transmissible but also perhaps less fatal than the other two coronavirus outbreaks.
How do you test for it?
To find the virus, doctors need to catch it in the act
, either by swabbing a sample directly from the nose and throat or in lung phlegm or by singling out the body’s immune response to the infection in a blood test.
The new strain has already been found in the lungs, nose, throat, even in faeces, says infectious disease expert Professor Raina MacIntyre. It can hitch a ride in the bloodstream to other organs such as the kidneys, liver, intestines and possibly the heart, brain and central nervous system, too. She says without a blood test yet available outside of China, throat swabs and nasal tests can sometimes come back from the lab as false negatives because the virus is actually replicating lower down in the lungs.
Professor Lewin adds, "Early on, you had doctors in China diagnosing just off chest scans because you can see that lung inflammation, even if it's not severe."
Still, infectious disease physician and microbiologist Professor Peter Collignon says it’s not yet clear if everyone gets the new virus in their lungs. “Finding it down there isn't a tipping point [for severity] by any means. Some children have it in their lungs but display no symptoms," he says. "But it might not have travelled all the way down from the upper respiratory area in every case."
What are the symptoms and phases of the illness?
Much of what we know about COVID-19 comes from studies of the first 55,000-odd cases in China, which found more than 80 per cent of people could fight off the illness without serious complications, even if they developed pneumonia. Lungs cleared, coughs eased and fevers broke. Anecdotally, some people have likened the infection to "three weeks in hell", racked by chills and struggling to breathe, while others have reported only a sore throat, a small cough, even no symptoms at all.
Hollywood actor Tom Hanks offered a rare public glimpse into life as a COVID-19 patient when he revealed he and his wife, Rita Wilson, had both tested positive while in Australia shooting his latest film. From hospital isolation on the Gold Coast, Hanks wrote of the illness's onset: "We felt a bit tired, like we had colds, and some body aches. Rita had some chills that came and went. Slight fevers too."
The main symptoms of the coronavirus
Based on data collected in China, most patients seem to have:
- Fever (88% of patients)
- Cough (68%)
- Fatigue (38%)
- Shortness of breath (19%)
A patient might also complain of chills, headaches or a sore throat, and nausea or diarrhoea have also been reported, though not in the numbers seen during SARS. Less than five per cent of cases so far involve a blocked nose.
Professor Collignon says patients generally appear to have mild symptoms for the first week or so. In severe cases, they can intensify into pneumonia during the second and, in rarer cases, the infection will turn unexpectedly deadly.
At the World Health Organisation, assistant director-general Bruce Aylward warns when danger strikes, it's often fast-moving. Doctors report patients can go downhill quickly during those "critical" second and third weeks and urge people with or suspected to have the virus to monitor their symptoms, particularly their breathing and fever.
