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 coronavirus that causes COVID-19 is officially called 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.
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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 alpha variant circulating in the UK at that time was also found in the Netherlands. The beta variant from South Africa and two variants from Brazil, gamma variant P1 and gamma variant P2, were detected in January 2021. In April 2021, the delta variant that was first identified in India was also found in the Netherlands. These virus variants appear to be more contagious than the previous one. 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. For the time being, 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.
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 Alpha variant, Beta variant and Delta variant and the Gamma variants P1 and P2 of the virus were detected in the Netherlands in the context of ‘pathogen surveillance’. Pathogen surveillance is a joint research programme in which RIVM, Erasmus MC and 21 laboratories in the Netherlands are working together. 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 virus 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 stay home and get tested by the Municipal Public Health Services (GGD).
Poster on coronavirus SARS-CoV-2 (COVID-19)
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How weather affects the virus
We know that many respiratory viruses spread less easily when the weather is warmer and sunnier. 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. Among other things, weather has an effect on our behaviour and on our immune systems. 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.
How the virus spreads
How does the coronavirus SARS-CoV-2 spread and what can you do to prevent it from spreading? See our page on The spread of COVID-19.