/This is what COVID-19 does to your body and why it can kill – ABC News

This is what COVID-19 does to your body and why it can kill – ABC News

When Anne Elliott moved to the UK in 2019 the plan was to enjoy a carefree working holiday before returning to Australia for the serious stuff: marriage, mortgage, kids.

Elliott, a critical care nurse, took a job at the Chelsea and Westminster Hospital in the heart of the city. A few months later COVID-19 had begun to spread and when the first wave hit the UK, she found herself on the frontline.

“We were completely blind-sided by the scale of it,” says Elliott who worked with critically ill COVID patients in the hospital’s intensive care unit. “We had no PPE. We had cardboard walls with duct tape to corner off sections of the emergency and ICU to COVID patients. It took us completely by surprise.”

As the weeks passed Elliott discovered first hand the damage COVID-19 could do. She caught the disease herself and although she recovered, it was months before she felt well again.

At work, Elliott cared for uncountable numbers of COVID-19 patients with stretched resources: watching on as the hospital’s medical consultants were forced to choose which patients would be given access to the top level of care and placed on a ventilator. She estimates roughly 40 per cent missed out.

“You might have two patients the same age but one has a history of medical conditions and you would have to think, who has a better chance of survival?,” says Elliott, who — like many of the nurses she worked with — now lives with “very, very prominent post-traumatic stress disorder”. “We were dealing with hundreds of patients a week and we only had so many resources. It was very hard to live with.”

Nine months later Elliott had zipped more than 50 patients into body bags. “That number of deaths was just me on my shifts, one nurse. It was really, really hard,” she says, her voice shaking at the memory.

One of the patients she lost was a young man her own age.

“He was born two weeks before me,” says Elliott, 31. “He had no prior medical history. We knew that he was very ill but one night he had a cardiac arrest.”

Now back in Australia, working at a large capital city hospital that is making preparations for an increase in COVID patients, Elliott wants to share her experience of fighting the disease.  

“I think it’s important to tell my story because it’s totally unimaginable [to people in Australia],” she says. “This virus can affect people in lots of different ways, young or old. It really doesn’t discriminate.”

But what does SARS-CoV-2 do to the body? And how can it take a life in just two weeks? Elliott and Dr Stephen Parnis, a Melbourne emergency medicine specialist who has worked with COVID patients, talk us through it.

A cyclist rides past a memorial wall for COVID-19 victims in London.

Reuters: Toby Melville

Phase 1: Viral replication

First of all, the virus must enter the body, commonly by being breathed in. Receptors in the nose and mouth allow the virus easy access to the cells of the body.

Once inside, it begins multiplying at a great rate, says Parnis.

Within days the amount of virus in the body starts to affect its functioning. Symptoms such as a sore throat, headaches or loss of smell and taste emerge. A person with COVID-19 may get tested or isolate about now and the immune system ramps up in an attempt to kill cells containing the virus before it advances further.

The immune response will kick in faster, stronger and more effectively for those who have been vaccinated, ideally suppressing the illness before it even causes noticeable symptoms. But unvaccinated people don’t recognise SARS-Cov-2 and it can take time for the immune system to learn how to attack it.

Parnis estimates that around 80 per cent of people mount an effective immune response that ultimately tackles and suppresses the virus.

What happens to the other 20 per cent?

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Play Video. Duration: 3 minutes 59 seconds

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Phase 2: Attacking the lungs

If a person’s immune system doesn’t respond in time, then the virus will begin to spread away from the nose, down the windpipe and towards the lungs, infecting more and more cells.

It continues through the branches of the lungs to air sacs, called alveoli, that sit at the end of these branches. This is where the disease begins to get serious.

In a healthy human body alveoli allow oxygen breathed into the lungs to cross over into the bloodstream from where red blood cells inside capillaries deliver oxygen via the vascular system around the body.

“We think the virus spreads through the body usually via the circulation and we think that the principal mechanism by which it does damage is via blood vessels causing vasculitis,” says Parnis, referring to inflammation that damages blood vessels.

When someone is infected with COVID-19 the immune system sends white blood cells to battle the virus where they release inflammatory molecules designed to kill off the virus. But it leaves behind fluid and pus that clogs up the lungs and disrupts the vital transfer of oxygen.

“If you get this widespread pneumonitis or vasculitis, then these vessels will start clogging up the air sacs and airways,” says Parnis. “They start clogging up with mucus as part of an inflammatory process that can also cause blood clotting, or thrombosis.”

An emergency physician like Parnis might find patients arriving at the hospital emergency department about now showing symptoms of breathlessness and rapid breathing as the body attempts to source more oxygen.

This stage of the illness marks another turning point: COVID-19 patients can react in one of two ways.

Some continue to fight the virus, the immune system is activated, and the patient can be helped by extra oxygen from nasal prongs – like those in the maligned advertisement we’ve seen on our televisions recently – or steroid medication such as dexamethasone which Parnis says helps to reduce the “storm of inflammation”.

But other COVID patients are not so lucky.

The infection can lead to Acute Respiratory Distress Syndrome which creates an oxygen-deprived state called hypoxemia. A deadly cycle begins.

The patient struggles to breathe as oxygen levels in the blood plummet, leading to mental confusion and delirium.

Parnis says that while a healthy body would have oxygen saturation levels of over 95 per cent, a struggling COVID patient can have oxygen readings in the 60s.

“If a patient presents in that way it would make your own heart race,” he says. “At that level of oxygenation you’re thinking this is big trouble, this person could go into a cardiac arrest if we can’t get on top of that oxygen level.”

It’s a scenario unsettlingly familiar to Elliott who remembers many patients arriving at the ICU struggling for breath.

“We used to get very, very distressed people coming up from the ward to ICU who were hypoxic and they were quite agitated, trying to rip everything off, breathing rapidly but they still couldn’t get enough air,” she says.

If you took an X-ray of a COVID patient’s lungs at this point in the disease you would see solid white patches where air spaces, that typically appear black on an X-ray, should be.

Those white patches represent the fluid, pus, mucus and dead lung cells that impair the lung and interfere with breathing and oxygen transfer. In a healthy respiratory tract little hair-like structures called cilia swish around and clear out debris and mucous, but in a COVID-affected patient the cilia are attacked and disabled by the virus.

Xray of badly damaged lungs

AP: Northwestern Medicine

At this point emergency doctors or ICU nurses like Parnis and Elliott will suggest a patient is ventilated, or intubated.

When this happens patients are critically ill. Who lives and who dies starts to become unpredictable.

Elliott recalls calling relatives so the patient could speak to their loved ones before the tube was inserted. “We’ve had people who were about to be intubated who wanted to call their relatives and explain what’s happening. That might be the last time people are actually ‘there’ [depending on how the disease progressed].”

Parnis explains that intubated patients are placed on their stomachs in a “prone” position which improves the effectiveness of ventilation.

They are also heavily sedated and paralysed, Elliott says, to stop the body’s natural reflex to fight against the machinery that is being pushed into their lungs and taking over their breathing reflex: “The treatment is too uncomfortable. Otherwise the patient would not tolerate it,” she says.

“Sometimes even with 100 per cent oxygen, you’re still pushing the wheelbarrow uphill,” says Parnis.

Meanwhile the virus is continuing its march through the cells of the body. The worst is not over yet.

Two women in blue plastic protective clothes and wearing face masks hug in a hospital corridor


Phase 3: Vital organs break down

The virus is doing deep damage to the lungs but with the rest of the body beginning to be deprived of oxygen other organs are also starting to deteriorate. The liver, heart, kidneys and intestines are particularly vulnerable.

As they begin to malfunction, their vital role in multiple life-sustaining functions is disrupted.

Many patients experience bouts of diarrhoea as the virus enters the cells of the intestinal tract causing inflammation and a leaky gut lining that can allow intestinal pathogens to escape into the abdominal cavity and reproduce.

The body is poisoning itself.

“A lot of monitoring goes on in intensive care,” says Elliott. “You’re looking at blood tests, you’re looking at chest X-rays, you’re projecting people’’s future based on how many drugs we are using to support their body, [or] their oxygen requirements. But this virus is completely unpredictable.”

A close-up of the Gekko ventilator in 2020, during the COVID-19 pandemic.

ABC News

Phase 4: The final struggle

The immune system increases its response in a desperate attempt to crush the virus.

In a cruel twist this extra effort creates what is known as a cytokine storm when the immune system starts striking out at anything in desperation, attacking healthy tissue as well as the virus it’s aiming to defeat.

This can cause blood pressure to plummet and blood vessels to “leak”. Blood clots can form alongside a high fever. Acidity of the blood increases, more fluid builds up in the lungs and makes lack of oxygen even worse.

Three health professionals in full PPE surround a patient on a ventilator

ABC News: Niall Lenihan

During this phase COVID-19 patients are often diagnosed with brain inflammation causing confusion, seizures and strokes. Similar inflammation is seen in the heart leading to increased incidence of blood clots and heart attack.

At this stage of the disease organs begin to break down leading to catastrophic organ failure. This is how people die.

A turn for the worse can happen literally overnight.

“They might be chugging along, doing okay and then the next day they go into cardiac arrest, or they might have significant kidney failure,” Elliott says. “Their lungs may just never have been able to recruit [oxygen] and there was no way for their bodies to correct what was happening.

“Some people get better and they go home. And then other people would just die. And then their bed would be taken up by the next person.”

What is next?

Parnis says Australia has a comparatively good survival rate for COVID patients in ICU, around 80 per cent survive at this stage of their illness compared with around 50 per cent overseas.

But he has a warning.

“The more pressure on the system, the more likelihood there is for those survival numbers to deteriorate,” he says.

Elliott says she is anxious about what will come next for Australia if the current NSW outbreak is not brought under control.

“I remember being in the UK and watching things unfold [in other countries] thinking ‘it’s not going to get that big’ then it became even worse,” she says.

“We nurses and doctors are supposed to save people’s lives. We’re not here to watch people die. Australia has one of the better health systems in the world and I hope we will be better equipped to deal with it. That will be our lifeline, I think.”

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Play Video. Duration: 2 minutes 43 seconds

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