Understanding Coronavirus (COVID-19)

Understanding Coronavirus: The Basics

Continuing our COVID-19 and Heart Disease series, Professor Bob Graham breaks down some key questions to help you understand how viruses like COVID-19 work, how they impact our bodies, and how they can be treated.

12 October 2020
Update 25 Nov 2021: Information from this article was accurate at the time of publishing and reflected the rules/advice announced by governing bodies at that time.

What is a virus?

A virus is a very small particle consisting of either a strand of DNA or RNA (the genetic material that like a roadmap has the code to make copies of the virus) covered by a coat of protein. It is so small that you cannot see with your eye—you need a powerful microscope. It can only live outside the body for a short time (hours to a few days). For a virus to multiply it needs to be inside the cells of our body. So, it needs to get into the body and infect the cells of our body. This is what the coronavirus, SARS-CoV-2, which causes COVID-19, as well as other viruses, do.

Why is SARS-CoV-2 very bad for us?

When SARS-CoV-2 infects us, it enters our cells and damages them so that they don’t work properly and can die. In addition, when it infects us, our body’s immune system tries to fight it and the chemicals that the body makes to do this, can themselves cause injury and deaths of our cells. These effects lead to damage, firstly, in our lungs, as they are generally the first organ to be infected when we breathe in the virus, but then the virus can also spread to other parts of the body and damage the heart, brain and kidneys.

Why do we need to sanitise or wash our hands with soap?

We do this because we can be infected by touching surfaces that have virus on them, and then we touch our mouth or eyes with our hands. The virus is coated with protein – small particles that are required for the virus to get into your cells. If you wash your hands with just water, it washes right over the top of the virus’s outer protein layer. But if you use soap, it breaks the proteins on the surface of the virus so it can no longer get into your cells. Similarly, when we sanitise our hands, the alcohol in the sanitiser destroys the proteins on the surface of the virus, so that it can no longer infect your cells.

Why do we wear a mask?

This is a very important question considering that the virus is very small. A mask is important for three reasons:

1. If you have the virus, it stops the spread from you to other people when you cough or sneeze or just breath out in confined spaces.
2. It stops you touching your face with your hands that may have virus on them as a result of having touched an infected surface.
3. Wearing a mask may also reduce the spread of virus to you from someone else who is infected, although physical distancing is much more effective for this, as described below.

It is important not to let the mask fall down below your nose and below your mouth, because then you’re breathing air from around the outside of the mask where there may be virus that has been trapped by the mask.

The best way to reduce the chances of getting COVID-19 from someone who is infected, is physical distancing. The virus is carried in tiny liquid droplets when an infected person breathes out, coughs, sneezes or sings, so staying well away (at least 1.5 metres) from people markedly reduces the chances that you will be infected.

If you want to take the mask off, take it off completely and put it in a bag plastic bag or throw it away. If it’s reusable then make sure that it’s in a plastic bag for you to take it home and wash. Always sanitise your hands after taking off the mask because you may have rubbed some of the outside of the mask that has virus on it, onto your hands.

How does the body deal with the virus?

As soon as the virus enters your body and cells, it is recognised as bad, and specific cells try to stop it from spreading in your body by literally gobbling it up like little ‘Pac Men’ and killing it. At the same time, your body releases certain chemicals that kill the virus. This is our first line of defence. Our second line of defence is antibodies. Antibodies are ‘Y’ shaped things that are in your bloodstream or your lungs. These interact with the virus and block its ability to get into your cells. However, unlike the first line of defence that is always present and waiting to attack viruses, antibodies have to be made after you get infected and this takes time (several days).

What is a virus dose?

This is the amount of virus that you get if someone coughs on you or you walk into a crowded elevator where somebody is infected. Imagine “dose” like cigarette smoke. That is, the more smoke you inhale, the more likely you are to cough. And in this case, it’s important because the more virus you get, that is, the bigger the dose, the more rapidly the virus can spread and make you sick. This is because a large dose can overwhelm our first line of defence and spread deep into your lungs before we have time to make antibodies.

What is the difference between a virus and a bacteria?

They are both small and need a microscope to be seen. However, viruses are even smaller than bacteria. More importantly, viruses need to be inside your body and inside your cells to multiply and live, but bacteria do not. Bacteria can live and multiply in dirty water, milk, other food as well as our body fluids. There are very good antibiotics that kill bacteria, but drugs that stop viral infections are more difficult to find and make.

What is a vaccine?

In the same way that a virus causes special cells to start making antibodies, we can set this process in motion just by using a small portion of the virus, which itself cannot cause COVID-19. When this is injected into you, it stimulates the production of lots of antibodies that specifically recognise and prevent the spread of the virus. Thus, the vaccine, by stimulating the production of antibodies, protects you if, in the future, you are exposed to the virus.

How easy is it to make an effective vaccine?

Making an effective vaccine that is not only safe when given to millions and millions of people worldwide, and that not only stops you from getting very sick but also prevents you from getting infected and, therefore, prevents spread of the disease, is enormously challenging. It requires very careful expensive testing in thousands of volunteers over many months, if not years, and testing in not only young people, but also older people who are less able to respond to a vaccine and, thus, less likely to benefit from a vaccine.

Are there any other ways of controlling the COVID-19 pandemic apart from a vaccine?

Possibly. With some sickness caused by viruses, such as AIDS, we have not been able to develop a vaccine, but we can control them effectively with drugs, although they have to be taken every day throughout your life. In addition, some drugs have already been found that decrease you chances of dying from COVID-19, and many more are being tested.