Are corona tests reliable?

Government policy

In 2021, the government wants to move to more widespread and more frequent coronavirus testing, including people without symptoms. This will create more opportunities to open up society and at the same time keep a good eye on (the spread of) the virus.

The RIVM states that testing for COVID-19 is an important tool in the control of the coronavirus. Based on the test results, progress in the fight against the virus is measured.

But, how reliable are corona tests?
The coronate test result itself does not provide certainty about whether or not someone is infected, but it does increase or decrease the likelihood that someone is infected or not. With a weak-positive result or a negative result, there is less certainty. Then one must take into account not only the test result but also any symptoms.


The National Coordination Structure for Test Capacity (LCT) and the RIVM is investigating how reliable coronate tests are. They are assessing whether the tests can be used and for whom. New (rapid) tests are only used if they can be done quickly, safely, and reliably. Before the tests are approved, a great deal of research has been done to ensure that the test results provide sufficient certainty.

Weakly positive results

In practice, two situations can occur: you test positive or you test negative for the coronavirus. With a positive test, there is a good chance that you are infected with the virus. With a negative test, there is a chance that you are infected after all, but that the test ‘made a mistake’.

However; even small amounts of genetic material from the coronavirus can cause a positive test result. This is called a weak-positive result. This can occur when:

  • one has only just been infected;
  • the test was not administered properly;
  • the contamination took place in the past.


With weak-positive results, a doctor also takes into account symptoms such as coughing, shortness of breath, loss of taste and smell. This allows the doctor to advise someone with a weak-positive result to quarantine or not. Conversely, if the test is negative, a doctor also looks for symptoms to rule out false-negative results as much as possible.


The coronavirus result in itself does not provide certainty, but only increases or decreases the likelihood that someone is infected with COVID-19 or not. With a weak-positive result or with a negative result, there is less certainty. Then one takes into account not only the test result but also any symptoms.

In general, the result of any test is more reliable at the time when you have just developed symptoms. Since December 1, 2020, even people who have no symptoms can get tested during their quarantaine from day 5.

Source: Ruben Mersch. How does the corona test work? The Correspondent..
September 14, 2020

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