What is COVID-19?
Last Updated: 14th May 2020
COVID-19 is the name of a new virus that causes respiratory illness. It was discovered in Wuhan Province China in December 2019 and is part of a family of virus' called Coronavirus.
A little like how there's so many different types of cats in the cat family, it's the same with the Coronavirus family. Some are relatively harmless house-cats like the Common Cold. Other Coronavirus are more like lions or tigers - for example MERS and SARS. In fact, the scientific name for COVID-19 is SARS-CoV-2 because it's been recognised as a new virus strain similar to the infamous SARS-CoV-1.
What happens if you get it?
Once in the body, COVID-19 makes its way to the lungs and targets cells used to keep the airways clear of mucus and debris. The virus uses these cells to reproduce more of itself, which ends with the cells dying and adding debris to the lungs. This creates an inflammatory response which starts to damage the lungs resulting in more debris. With the virus disabling the cells normally assigned to mopping up, debris begins to accumulate. This creates more inflammation, which creates more debris, which causes more inflammation and a cycle begins . This can continue for a few days before a person develops symptoms. The time it takes to show symptoms is different for everyone. It can be as short as 2 days, or as long as 14. For most people they will notice symptoms on Day 5.
Even before showing symptoms, a person is infectious. The virus sheds itself from the body mainly in microscopic droplets. For example sweat, or most commonly, through vapour when a person talks. If you've ever watched fog come from someones mouth on a cold winters day, then you've seen a visualisation of the vapour people expel when talking.
Whilst most people experience mild to moderate symptoms, some need to be hospitalised. This percentage has varied in different countries. In China, 19% of cases needed a hospital bed whilst in Europe it's been 32%.
For serious cases of COVID-19, inflammation continues to increase in the lungs to the point where Pneumonia develops. Pneumonia is a condition where the lungs begin to fill with fluid instead of air. The condition can range from mild, to life-threatening.
Severe and critical cases often progress into a unique form of Acute Respiratory Distress Syndrome (ARDS). ARDS is a serious illness resulting from a large build up of fluid in the lungs. When this happens, immune cells flood the lungs to address the increasing inflammation. Sometimes, COVID-19 confuses the cells which can then begin killing anything in their path. 30-45% of ARDS cases are fatal and often require advanced life support.
ARDS treatment usually involves providing supplemental oxygen and mechanical ventilation. This is machinery that increases oxygen in the body as well as helps the lungs breath in and out. The goal is to get more oxygen into the bloodstream when the lungs can't. If the lungs are too full, this treatment doesn't work. Without an ability to oxygenate the bloodstream, organs begin to struggle and inevitably fail. Multiple organ failure is a common way to die from COVID-19.
Even if a patient survives they may be left with permanent lung damage. For example SARS-CoV-1 left holes in people lungs and 30% of MERs survivors were left with scars. It's to early to tell what the long term health effects are for those who recover from COVID-19 but early indications suggest there will be long term effects for some survivors. A study of CT scans from 70 survivors in China showed 94% left the hospital with signs of damaged lungs . And doctors are starting to expect other organs may experience long term affects too.
COVID-19 Infection Explained
How dangerous is it?
Because COVID-19 is a new disease, there's a lot we don't know. In general - whether a disease is considered dangerous is often a combination of:
- How severe the illness is when you contract it and,
- How quickly it spreads
Severity of Illness
From a sample of 55,924 confirmed cases in China observed WHO noted:
- 81% experienced mild to moderate symptoms
- 14% experienced severe symptoms requiring hospitalisation
- 5% suffered from critical symptoms requiring ICU
We're still learning a lot about COVID-19 and a specific fatality rate is currently unknown. It's likely to be somewhere between 1-2% but this remains unclear. By comparison the H1N1 Swine Flu pandemic had a fatality rate of 0.02% and SARS was 15%. For a deeper exploration of fatality rates read here.
Fatality % Changes Over Time
Fatality rates are difficult to calculate in the middle of an outbreak. They change over time, and will be different in different countries. Australia has one of the lowest fatality rates whilst countries like the UK, Sweden, the Netherlands and Italy initially experienced some of the worst.
Pre-Existing Conditions at Risk
In Italy, most of those who died from COVID-19 had multiple comorbidities. In fact only 3.6% of those who died had none. 14.4% of fatalities had one, 21.1% had two, and 60.9% had three or more. The most common comorbidities were existing conditions that lowered the bodies immune system or weakened important internal organs.
How easily and quickly a disease spreads correlates to its level of danger. For example H1N1 (Swine Flu) was a 2009 pandemic that only had a fatality rate of ~0.02%, but was infectious enough to spread to millions of people and cause hundreds of thousands of deaths. Interestingly COVID-19 is currently thought to be twice as contagious as H1N1 and at least five times more fatal.
High transmission rates combined with high hospitalisation rates is a combination that has concerned many governments.
One of the reasons COVID-19 spreads so quickly, is that you can be infectious without having symptoms. It's currently thought people with COVID-19 can be infecting others just two days after being infected. Most people average symptoms on Day 5 and those with moderate, severe or critical illnesses can still be contagious even when in recovery.
What are the symptoms?
COVID-19 symptoms can range from a mild cough to severe shortness of breath. A percentage of individuals also show no symptoms, referred to as Asymptomatic. The percentage of asymptomatic cases is currently unknown and being actively studied. At this time it is not thought there is a high percentage of asymptomatic cases. Read more about Asymptomatic cases here.
If you're concerned you may have COVID-19, you can use this online symptom checker:
How does it spread?
The virus spreads from an infected person in microscopic droplets. This could be through a cough, a sneeze, or simply from skin oils left behind from touching a surface or object.
A person becomes infected when the virus enters the body. This happens most commonly when a person brings infected hands or other surfaces close to their mouth, nose or eyes. Or from spending extended time in close proximity to someone else infected.
How do you avoid COVID-19?
Regularly and thoroughly wash hands with soap and water for 30 seconds. Or clean your hands with an alcohol-based hand rub. Washing hands works because soap and alcohol effectively dissolve the outer shell of the virus leaving it vulnerable. Whilst COVID-19 is difficult to get rid of once it's in your body, it's easy to get rid of before it enters your body.
Maintain at least 1.5 metre distance between yourself and anyone who is coughing or sneezing. This is because even when someone speaks, they expel small water droplets in front of them. If you've ever watched fog come from someones mouth on a cold day this is what you're observing. 1.5m is generally enough for this fine mist not to reach another person.
Don't Infect Yourself
Avoid touching your eyes, nose and mouth. This is because our hands are a common source of infection. If they're infected then bringing your hands to your eyes, nose and mouth, gives the virus a way of entering your body.
Stay Home if Unwell
Stay home if you feel unwell. This is because if you have COVID-19, staying home prevents others from catching it. Even if what you have isn't COVID-19, staying home also allows you to protect other peoples immune systems from fighting what you have.
Seek Medical Care Early
If you have fever, cough and difficulty breathing, seek medical care early. If you have COVID-19, the earlier you can get tested, the sooner you can get medical support, and the easier your journey should be.