Practical information about testing
Practical information about testing can be found at Government.nl. If you have symptoms, you can make an appointment to get tested. You can also be tested if you were in close contact with someone who tested positive for COVID-19, even if you do not have symptoms. There are also other exceptions in which testing without symptoms is possible. The same website also contains information about the test results.
Why is testing important?
It is important for people to get tested if they have symptoms. This ensures that new infections will be detected sooner. People who do turn out to have the virus will go into isolation and stay home so they cannot infect others. The Municipal Public Health Services (GGDs) start source and contact tracing and recommend quarantine for household members and close contacts. Quarantine applies if household members and close contacts are not fully vaccinated, and/or have not had a COVID-19 infection in the past 6 months. This helps to prevent the person with COVID-19 and their close contacts from infecting others. Testing is important in order to curb and monitor the spread of the virus.
Vaccination, testing and measures
Once people have been vaccinated, the vaccine will protect them against the virus. However, a person who has been vaccinated must still keep following the measures, just like everyone else, until enough people in the Netherlands have been vaccinated. There are a number of reasons for this. The vaccines work well and are safe. However, there is a chance that you may become infected with the virus, even if you do not become seriously ill from it. By now we know that vaccination also reduces the transmission of the virus from one person to another. However, vaccinated people can still infect others. For that reason, following the measures is still important.
Types of tests
There are various types of tests. Which types are there, and what do they tell us?
The PCR test
The PCR test detects specific fragments of genetic material from the coronavirus SARS-CoV-2. It is the most widely used and most reliable test. A smear is taken from the nose and throat with a cotton swab. This sample goes to a laboratory for the PCR test. The PCR test involves making copies of a small part of the virus. A small fragment of genetic material from the virus is replicated repeatedly, in order to detect its presence. The PCR test has a high test sensitivity. That means that the PCR test also detects the virus in someone who is not carrying much of the virus yet, or no longer has much virus left in their body.
COVID-19 testing for children
To control the spread of the virus, it is important to test as many symptomatic children as possible. Children without symptoms should also be tested if the teacher or another child in their classroom has tested positive for COVID-19. A testing method designed specifically for children can help.
RIVMNational Institute for Public Health and the Environment investigated whether it would be possible to use a testing method adapted more specifically for children without making the test much less reliable. Reference literature and validation research by GGD West-Brabant and GGD Amsterdam among adults shows that this can be achieved by mid-turbinate nasal sampling (mid-turbinate refers to the middle of the nasal conchae, above the inner nostril). Using this method, the nasal swab is inserted less deeply into the nose: 1-2 centimetres depending on age, rather than 5-7 centimetres. Mid-turbinate nasal sampling is slightly less reliable than the current, deeper nasal sampling method. That is why the less deep specimen of nasal mucus is taken in conjunction with the current throat swab.
Children aged 12 years and under who go to a GGD test lane will be tested using this new method starting no later than 4 April. Municipal Public Health Services (GGDs) focus extra attention on younger children who get tested. Read more in the GGD GHOR news item about the updated testing method (in Dutch).
Video on testing children for COVID-19
The LAMP (loop-mediated isothermal amplification) test, like the PCR test, is a form of testing in which small fragments of genetic material are copied or replicated. The method used for that purpose in the LAMP test is completely different from the PCR test. The major advantage of the LAMP test is that the fragments of genetic material are replicated at only one temperature. Therefore, this test is faster than the PCR test, which requires fluctuations in temperature. The LAMP test requires different equipment and chemical substances than are needed for PCR tests. As a result, they can complement each other in this respect, rather than competing if supplies become scarce.
The antigen test
The antigen test detects the presence of antigens for SARS-CoV-2 in nasal and/or throat mucus. Antigens are fragments of the virus (proteins) that can produce an immune response in the body. If you are carrying the virus, the antigen test will quickly show that result – usually about fifteen minutes after applying the sample to the test set. The test can also be used outside a laboratory setting. The antigen test is less sensitive than the PCR test, especially if the level of virus particles is low. Someone who is not carrying much of the virus yet, or no longer has much virus left in their body, and is therefore not yet or no longer contagious, will often test negative on an antigen test. In that case, a person may wrongly get a negative test result, even if they may have COVID-19, or had it in the past.
Self-test (antigen test)
An antigen self-test is a COVID-19 test that you can buy in a shop, chemist or pharmacy to test yourself.
Self-tests are intended for people without symptoms, as a supplementary tool to identify infections that would otherwise go undetected. Self-tests are not suitable for:
- people with symptoms
- people who had contact with someone who has COVID-19
- people returning from a high-risk area
Self-tests are less reliable than a PCR test or antigen test done by a professional. Research shows that self-tests are between 58% and 78% reliable, as long as the self-test is used properly. That means there is a reasonable chance that someone may receive a negative test result on a self-test, even if the person is infected with SARS-CoV-2 and may be able to pass the virus to others.
A positive result from a self-test must always be confirmed with a professional PCR test or antigen test by the GGD.
This test is primarily used for research and screening at the population level, by selected laboratories. The serological test determines if there are specific antibodies against the coronavirus SARS-CoV-2 in your blood. Antibodies are part of your natural defences: the immune system. The body produces them in response to an infection with the virus. It can take 2 to 3 weeks for your body to produce the right antibodies and release them in sufficient quantities in your blood, so they can be detected. A serological test involves taking a blood sample. The test shows if you have had the virus.
Breath test (breathalyser)
The PCR test and the antigen test are tests that have been used in medical laboratories for many years to detect the presence of other diseases. Tests for the coronavirus SARS-CoV-2 are also being developed that are based on less frequently used principles. One of those tests is the ‘breath test’ or breathalyser, also known as the electronic nose. Exhaled air is examined for molecules that indicate that you are infected with the virus. This test is mainly suitable for excluding the possibility that you are currently carrying the virus. A breath test can exclude the possibility of infection, but is not able to detect the presence of infection as precisely. A ‘positive’ breath test must therefore always be confirmed with a different test, such as a PCR, LAMP or antigen test.
When should each type of test be used?
As other types of testing become available, it is important to take a close look at how and when certain tests can be used in practice. Each test has its advantages and disadvantages, such as the speed of the result, the place where the test can be done (inside or outside a laboratory) and the sensitivity of the test. In certain situations, a false-negative result can have serious consequences. Examples include people who are seriously ill as well as vulnerable people in institutions. In such cases, it is important to use a test that is as accurate as possible. The PCR test is the best option for this purpose. The PCR is the ‘gold standard’, and the LAMP test is considered equivalent.
In situations where the disadvantage of a false-negative test result outweighs, for example, speed and flexibility, less accurate tests can also be used. Like the antigen test. The breath test is a test that can be used as pre-selection; if the test is positive for COVID-19, it is important to always use a second test to confirm.
The Outbreak Management Team advises the Cabinet about which individuals or groups can be tested with which type(s) of test. A clear table shows which test could be used in different situations.
Testing with and without symptoms
In general, the results of each test are more reliable when you have just developed symptoms. From 1 December 2020 on, people who do not have symptoms can also get tested during their quarantine period from day 5 on.
The role for RIVM in testing
RIVM draws up the guidelines and protocols for testing and for source and contact tracing in cooperation with the professional field. The Municipal Public Health Services (GGDs) and hospitals carry out the tests. The quality of the tests being offered is monitored closely. RIVM is also researching various aspects of the SARS-CoV-2 virus and the disease COVID-19. For example, RIVM is researching various types of tests and compiling data from various studies being conducted by other Dutch laboratories, combining the data so that the laboratories can learn from each other and make well-informed choices regarding certain tests.
RIVM is also researching such topics as which antigen and antibody tests yield the most reliable results. RIVM has advised that the antigen test is suitable as self-test for consumers. Manufacturers of rapid antigen tests who want to market them as self-tests need to request a temporary exemption. RIVM supports the Ministry in granting these exemptions. Read more about self-testing.
WHO Reference Laboratory
RIVM is a WHO reference laboratory and develops various diagnostic tests for the coronavirus SARS-CoV-2. These diagnostic tests are checked along with international partners. The techniques are then rolled out to laboratories at home and abroad. The labs report the results of quality assessments to RIVM. RIVM looks at how a lab operates compared to other laboratories. Watch this video on the reference laboratory.
Testing capacity in the Netherlands
The Dutch Government, together with the Municipal Health Service (GGD) and the National Coordination Team Diagnostic Chain (LCDK), ensures that there are enough test sites, test materials and laboratories that can test for the coronavirus SARS-CoV-2.