Viruses are micro-organisms. They are so small that they cannot be seen with an ordinary microscope. A virus cannot do anything on its own. Essentially, a virus particle is no more than a piece of genetic material – deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) – enclosed inside a layer of proteins. There are many different types of viruses.
How a virus works
Viruses cannot exist and thrive without a host. A virus needs host cells from a living creature, for example a human. Inside the host, the virus penetrates the healthy cells and then starts replicating itself. The cell very quickly produces a huge number of virus particles known as virions. The new virions that are released go on to infect new cells. That is how a carrier of the virus becomes ill.
Once your immune system detects the presence of these virus cells, it responds in various ways – for example by creating antibodies, which try to destroy the virus. Those antibodies remain in the body for some time, even after you are completely recovered. Based on those antibodies, it is possible to see if you were previously infected.
The novel coronavirus
There are many different types of viruses, including a family known as the ‘coronaviruses’. Examples include the coronavirus that causes Middle East Respiratory Syndrome (MERS-CoV) and the coronavirus that causes Severe Acute Respiratory Syndrome (SARS-CoV1) and was the virus behind the SARS epidemic in 2003. The most recently discovered coronavirus causes the disease known as COVID-19. The official name of this novel coronavirus is SARS-CoV-2.
The novel coronavirus is thought to have moved from animals to humans in China. A coronavirus has a striking and specific shape. If you look at the virus under an electron microscope, you will see that it is covered in club-shaped spikes. The overall form resembles a crown. The Latin word for crown is ‘corona’. The name of the virus comes from its shape.
Changes in the virus
Many viruses change over time. The main question is whether these changes make the virus more dangerous or less dangerous to humans. Fortunately, it is very rare for a virus to change in a way that suddenly makes it very dangerous. As a precaution, these changes are always closely monitored. The novel coronavirus originated as a human virus in one single location in China in December 2019. Since then, the virus has travelled all over the world, and its genetic code has changed slightly along the way. The guiding principle is: the more different variants of the virus are circulating, the harder it is to make a vaccine and eliminate the virus
How climate affects the virus
We know that many viruses spread less easily in warmer and sunnier climates. Weather and climate do not have much influence on the spread of this novel coronavirus. The virus has also spread in countries with a warm and sunny climate. There is no evidence that it will spread less quickly or disappear as the weather grows warmer.
If you are ill
There is a separate page about COVID-19, the disease caused by the novel coronavirus. Read all about the disease, the symptoms, and what to do if you think you have COVID-19.
The spread of the virus
How does the novel coronavirus spread and what can you do to prevent it from spreading? See our page Spread of COVID-19