Frequently Asked Questions
There are three types of tests: the standard PCR test, the Antigen rapid test and the Antibody rapid test. They all measure something different and the results are not directly comparable.
A PCR tests works with a sample taken from the nose or throat. Your sample goes to a laboratory, where it will be examined. This is done by searching for pieces of genetic material from the coronavirus, referred to as RNA. A positive result means that virus particles have been found in your sample. This does not necessarily mean that you are contagious and can pass on the virus. The test can show very accurately whether you have the RNA of the virus in your body. To be sure, the sample must first be further examined, by means of a virus culture. Only then you know for sure if someone is contagious. PCR tests are very sensitive. They can find particles of the virus up to one month after the infection. In exceptional cases, the virus can even be found up to three months after the infection. It can therefore happen that you test positive, weeks after you have already been cured. A negative test means that you probably weren’t infected when the test was taken. In that case you don’t have to do anything, quarantine is not necessary. At the moment the PCR is the gold standard for diagnosis of COVID-19.
With an antigen test you also get a cotton swab in your nose or throat, just like with a PCR test. Afterwards, however, the sample is analyzed on the spot. You can read the result immediately, often within fifteen minutes. Antigen tests are therefore also called “rapid tests”. A positive result means that you have an active infection. So, you should definitely quarantine. The chance is small that it is an infection from the past that is still picked up, which can happen with a PCR test. A negative result means that you most likely don’t have an active infection and can pass on the virus. Antigen rapid tests are designed to measure only infectious infections, i.e. infections that fall within the infectious period. Rapid antigen tests are easy-to-use, low-cost and highly scalable, which makes them suitable for widespread screening for COVID-19 infectivity.
With an antibody rapid test, a blood sample is taken. This can also be analyzed on the spot, and you can read the result immediately, often within fifteen minutes. If antibodies are found in your blood, you test positive. Your body made those antibodies to defend itself against the virus. So, you have been infected in the past. If you test negative, you probably wouldn’t have been infected in the past. You therefore have no antibodies in your blood. Note that the number of antibodies decreases sharply in the months after the infection. So, it is possible that you test negative, even though you were once infected.
“No doubt: rapid tests quickly give us more freedom”
Jaap Goudsmit is a doctor and virologist associated with the Harvard T.H. Chan School of Public Health and scientific director of the Human Vaccines Project, an NGO that tries to understand our defenses against disease so that faster and better vaccines can be made.
On 19 October 2020 he published an article in which he gives his opinion on rapid tests “No doubt: rapid tests quickly give us more freedom”. He argues: “The current PCR tests could excellent show infections. New rapid tests are better to detect people who are likely to spread the virus, and thus to prevent spread”.
About a negative result of an antigen tests, he says: “On the basis of such a negative test, I would dare to grant people access to a café, restaurant or stadium, and in case of positivity to refuse access and send to the GGD for confirmation for a PCR test.
“The rapid protein test therefore seems less sensitive than the PCR variant.”
This says Marije Hofstra, clinical microbiologist at the UMC in Utrecht, on 7 October 2020 in the Dagblad van het Noorden.
Hofstra: ,,This occurs when the amount of virus present is very low. We see this, for example, in people who have had complaints for some time. That doesn’t have to be a problem, because people with a lower amount of virus probably contribute less to new infections”.
“The super-fast tests – ready in a quarter of an hour – represent a potential breakthrough for the stalled testing policy. The protein test can be used to directly monitor and control large groups – e.g. personnel in care and education – so that test lanes and labs do not become overloaded”.
We offer a new concept of COVID-19 screening of your employees so that you can remain open safely. This concept consists of two elements: self-testing with a user-friendly test under medical supervision (Testen onder Supervisie).