Currently it is not recommended to use serological tests for the diagnosis of coronavirus, says Prof. Katarzyna Dzierzanowska-Fangrat, national consultant in the field of microbiology, in an interview with Rynek Zdrowia.
Serological tests may give false negative results
Since the beginning of the coronavirus pandemic in Poland the problem of too few tests carried out in Poland compared to other countries has been raised. Some environments postulate to allow the cluster serological tests to diagnose COVID-19. They would be cheaper than currently used molecular tests and the result would be available faster.
However, as it turns out, such tests may give false negative results. Therefore, they are not currently recommended for coronavirus diagnostics. This is confirmed by Prof. Katarzyna Dzierzanowska-Fangrat, national consultant in the field of microbiology, in an interview with Rynek Zdrowia. All because the serological tests are based on the detection of antibodies, which are produced by the human body in response to coronavirus. Their presence confirms the infection, but a negative result is not evidence of the lack of such infection. All because the test can be carried out during the so-called serological window, when the infected organism has not yet managed to produce antibodies. Because COVID-19 is a new coronavirus, it hasn’t yet been thoroughly diagnosed. Therefore, it is currently not known how fast the antibodies appear and how dynamic they are.
Molecular testing gives a clear result
Therefore, at present in Poland, according to WHO recommendations, tests based on molecular biology techniques are used. They give a clearly negative result. In Poland as of March 17, nearly 8,000 molecular tests for coronavirus infection were performed. Currently, such tests are performed by 19 laboratories all over Poland. During the last day, they examined about 1,200 thousand samples. The number of tests carried out is to grow gradually in the following days.
On the other hand, it is not excluded that serological tests will be available to some extent for coronavirus diagnosis, informs Rynek Zdrowia. The positive result of the serological test is unambiguous and does not raise doubts. If the possibility to perform such tests, for example privately, was introduced, it might be possible to identify some of the infected persons who do not show any symptoms of the disease. However, the great danger is that a negative (or maybe a false negative) result could dull the patient’s vigilance. Therefore, any such tests would require close medical supervision.