The coronavirus SARS-CoV-2 is the virus that can cause the disease known as COVID-19. The virus is spread through human-to-human transmission. Coughing and sneezing spreads small droplets. Someone else can breathe them in and become infected. The droplets can also be transmitted through hand contact, for example if someone touches their nose or face and then shakes hands.

About viruses

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 coronavirus SARS-CoV-2

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 coronavirus is SARS-CoV-2.

The coronavirus SARS-CoV-2  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.

Visual COVID-19: name coronavirus and why a virus needs humans

Download the infographic COVID-19: from infection to symptoms

A virus changes constantly

Viruses are constantly changing. The novel coronavirus designated as SARS-CoV-2 originated as a human virus in one single location in China in December 2019. Since then, the virus has been travelling all over the world, and its genetic code has changed slightly along the way; this is referred to as a mutation. There are thousands of variants of the virus by now. Various mutations of the virus have been circulating in the Netherlands since spring. Those variants are monitored closely. 

Variants of the virus  

Pathogen surveillance is used to monitor whether new variants of the coronavirus SARS-CoV-2 are occurring in the Netherlands, in addition to the variants that are already known. In December 2020, the virus variant circulating in the UK was also found in the Netherlands. In January 2021, a virus variant from South Africa and two variants from Brazil were found. These four virus variants appear to be more contagious. Whether that is in fact the case is currently being investigated. Among other things, this requires laboratory research to examine the characteristics of the virus.  In addition, various studies are being done, such as epidemiological research;  this allows us to see how a virus variant is spreading. In the next few weeks, the weekly epidemiological update from RIVMNational Institute for Public Health and the Environment will also include the current situation regarding the spread of the different virus variants. 

Read more about the different variants of the virus

Research on variants of the virus

Random samples are taken in the Netherlands on an ongoing basis to research the virus and determine whether it is changing. The UK variant of the virus was detected in the Netherlands as part of a joint research programme in which RIVM, Erasmus MC and 21 laboratories in the Netherlands are working together. This is called ‘pathogen surveillance’. The laboratories regularly send a random sampling of the test samples to RIVM or Erasmus MC, where they are examined. This makes it possible to map which variants are occurring in different locations in the Netherlands. This research is called sequence analysis. 

Prevent the spread, follow the measures

The current measures in the Netherlands are important to prevent the spread of the coronavirus (SARS-CoV-2), regardless of which variant it is. Prevent the further spread of the virus by following the measures: always stay 1.5 metres apart, limit the number of people you have contact with, stay home as much as possible, wash your hands frequently, and if you have symptoms, stay home and get tested.

Visual on spread and infection COVID-19

Download the infographic COVID-19: from infection to symptoms

How climate affects the virus

We know that many respiratory viruses spread less easily in warmer and sunnier climates. It is plausible that the same effect will apply to SARS-CoV-2.

There are multiple factors that could play a role in this seasonal variation. These factors could affect both the virus and its host. However, it is not the case that the virus will vanish in summer. The virus is also spreading in countries with a warm and sunny climate.

If you are ill

There is a separate page about COVID-19, the disease caused by the coronavirus SARS-CoV-2. Read all about the disease, the symptoms, and what to do if you think you have COVID-19.

Visual the coronavirus makes you ill

The spread of the virus 

How does the coronavirus SARS-CoV-2 spread and what can you do to prevent it from spreading? See our page Spread of COVID-19.