From Stuff. A very good report
A cough, a clammy forehead, shadows on the lungs. Most people infected in the viral pandemic now sweeping the globe will come down with just a mild dose. Some won’t know they’ve had it at all. But when it’s bad, the mystery virus 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 127,000 people since December.
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 in use 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.
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 pubic 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 per cent of patients)
- Cough (68 per cent)
- Fatigue (38 per cent)
- Shortness of breath (19 per cent)
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.
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 those with or suspected to have the virus to monitor their symptoms, particularly their breathing.
WHAT CAN GO WRONG DURING THE INFECTION?
On scans, they call it ground glass – a white mist over the usual empty black of the lungs. In some cases, there are bright spots, eerily similar to the “honeycomb-shaped” lesions left by SARS, but mostly Covid-19 makes a finer and more-even pattern across both lungs.
This inflammation is a sign the body is fighting back against the virus – in that battle, the lungs are ground zero. But Collignon warns sometimes the collateral damage can be worse than the bug itself.
As the immune system ramps up its defences, blood vessels start to leak and the lungs can be flooded with cellular debris, making it harder for them to pump oxygen to the rest of the body – and harder for patients to draw breath. “They start to drown,” Collignon says.
Falling blood oxygen levels put pressure on other organs, in particular the heart. More systems can start to fail, and blood pressure too, which, if it falls low enough can tip the body into septic shock, a whole-body infection.
“Even if the virus spreads to the heart or the kidneys and damages them, the real cause of death is still probably going to be oxygen levels falling and setting everything else off,” Collignon says. “If you’re an older person or already unwell and those organs are weaker, it can be the straw that breaks the camel’s back.”
While there is a theory that people with already compromised immune systems might escape this effect and so cope with an infection better than expected, Collignon warns they are especially vulnerable to the other big killer – co-infection.
Usually being hit with two bugs at once is rare, though not impossible. But as the virus chews through cells, it leaves the lungs less able to filter out germs picked up from the nose and throat – and wide open to a case of the flu or even a bout of bacterial pneumonia. (The first man to die from Covid-19 in Thailand was also sick with dengue fever.)
During the deadly 1918 Spanish Flu pandemic, most victims died not from the original virus but due to these second-wave bacterial pneumonia infections.
THE RISK OF DYING IF INFECTED WITH Covid-19 (BY AGE GROUP)
SO WHO IS AT RISK OF SERIOUS COMPLICATIONS?
So far, the WHO reports about 14 per cent of cases become severe, with serious breathing difficulties and falling blood oxygen levels. Another 6 per cent have been pushed into critical care – as multiple organs begin to fail alongside the lungs or septic shock sets in.
About 3.4 per cent have died. But Collignon expects the real death rate is actually much lower, given so many mild cases will likely go undiagnosed.
While anyone can catch the virus, very few children have suffered serious cases – a phenomenon also observed during SARS. Older people and those with other conditions such as diabetes or heart disease are most at risk of fatal complications. (“Over the age of 50, the immune system starts to fall apart,” MacIntyre explains).
But in Italy, where the virus has now gained a particularly deadly foothold, doctors are warning that younger patients (in their 40s and 50s) are also presenting to overwhelmed emergency departments needing help to breathe – some have even raised the prospect of an age limit for intensive care to free up beds for younger cases as life-saving machines such as ventilators become worth their weight in gold.
RISK OF DYING OF Covid-19 WITH A PRE-EXISTING CONDITION
Smokers are also considered more at risk, as early studies show the same cell receptors the virus hijacks in the lungs increase with cigarette smoke.
Some researchers have even pointed to higher smoking rates among men in China as a reason why less woman appear to be dying from the virus, although others are examining hormonal factors.
Whatever your personal vulnerability, the dose of virus you first receive – say, from touching a contaminated door knob versus caring for an infected person over several days – also plays a big part in how your body copes. “The higher the dose the faster you will get sick, and the harder it will be on you,” MacIntyre says.
That could explain why otherwise young and healthy medical workers have died from the disease. Li Wenliang, the 34-year-old doctor who blew the whistle on early cases of Covid-19, went through a gamut of treatments after falling ill himself, including antivirals, antibiotics, even having his blood pumped through an artificial lung, but he died weeks later.
As with SARS, clusters of severe infection are emerging in hospitals and households as people come into sustained close contact.
HOW DO DOCTORS TREAT THE CORONAVIRUS?
Despite the breakneck speed of global research, a vaccine for Covid-19 is still about a year away. And, while antivirals that block viruses such as Malaria, Ebola and HIV are being trialled against the new disease in some parts of the world, treatment is largely about managing complications – providing oxygen, keeping up fluids and monitoring how the body is coping.
Antibiotics don’t work on the virus as it is not caused by bacteria but they can be deployed against secondary infections. If breathing starts to fall, respirators and other measures will kick in to keep the lungs going.
As Lewin explains, doctors have a key choice when treating any new virus: is it better to block it directly with antiviral therapies as in the case of HIV or should they also dampen down the body’s immune response using drugs such as Interferon, to minimise the fall-out damage?
“Sometimes that can help but sometimes it means the infection overwhelms,” Lewin says. “It didn’t work with SARS but there’s been some success with MERS. Already for this, there’s been candidate [therapies] that look good in test tubes, but we need trials. China has about 70 going, testing different [approaches] but they’re actually struggling to enrol people now as cases fall.”
Collignon thinks it unlikely any of the treatments being tested will save the day before a vaccine hits the market – without larger trials, he warns, small studies can miss big problems on roll-out.
Experts also warn of increased pressure on hospitals (and available ventilators) if severe coronavirus cases hit wards all at once. While Australia’s healthcare system is strong compared to other countries, it’s population is also older, MacIntyre notes, meaning more demand for intensive care. To slow down the virus and avoid a “pinch” around flu season, doctors are calling for stricter containment measures such as self-isolation and social distancing, including bans on mass gatherings such as sport matches.
HOW LONG DOES RECOVERY TAKE AND IS THE DAMAGE PERMANENT?
MacIntyre says it’s too early to say if this disease will result in any permanent damage – such as the lung tissue scarring seen in some SARS and MERS cases. But a full recovery typically takes about a month (and can be longer again for severe cases).
So far, close to 70,000 people have already recovered worldwide. Now with antibodies in their system to fight off the virus, many experts expect they will remain immune for some time, though it is unclear for how long.
There have already been cases of people discharged from hospital with a negative test, only to test positive again days later or, in the case of one woman, more than a month down the line.
But while experts say it’s possible to be re-infected again it’s more likely the virus was still in their system. New studies have even suggested the virus could lie dormant in other parts of the body for weeks – with the longest period of infectiousness recorded as 37 days so far.
Back in Wuhan, Reed’s own self-quarantine ended weeks ago but, as with tens of millions of people in China, he has been living under lockdown since January in an unprecedented, but seemingly effective, government effort to stem the virus’s spread. UK-born Reed now hopes to return to Brisbane where he grew up and his family live.
“I’m likely immune now and I know I’ve gotten really lucky. But it’s a ghost town here. I can’t work, no one can. I’m stuck.”
If people were feeling unwell, they should ring Healthline on the dedicated Covid-19 number: 0800 358 5453. Or ring their GP before showing up at the practice and they would be advised what to do.