Research from the United States – The pitfalls of the Corona test, according to a study, the conventional PCR Tests are often negative, even though people are infected. Especially in the first days after infection, incorrect results are piling up.Berit Uhlmann2 Kommentare2Es can be that badly made smears affect the test result. To this end, a large-scale American study. A man can be in Istanbul on Covid-19 test. Photo: Sedat Suna (Keystone)

thousands of people experience every day around the world, the proceeds of the Moment: Negative, no Sars-CoV-2 of which are lockable. Everything is good so. Really? Not necessarily, is the conclusion of a study published in the journal “Annals of Internal Medicine”. In it, researchers at the Johns Hopkins University warn that the commonly used PCR Tests alone are very strong. The scientists working with the Doctor Lauren Kucirka evaluated in a review of seven studies, more than 1300 test results contained.

according to The analysis, at least 20 percent of the Tests yielded a result that was falsely negative. In fact, the patients were infected, what was reflected by the fact that more Tests were positive. Also, in part, have antibodies to the Virus in the supposedly non-Infected.

The first Tests on the eighth day

showed at the same time, the time of sampling plays a big role for the validity of the result. In the first three days after infection, it was virtually impossible for virus type Sars-CoV-2 to prove. So early on, the Tests were virtually worthless. Smears of the fourth day, gave in two-thirds of all cases of mistakenly all-clear. On the fifth day – the date on which typically the onset of symptoms – an average of 40 percent of the results are false-negative. The error rate was reduced then to 20 per cent, on the eighth day and then slowly again.

Even if these data contain uncertainties, the results conclude that the most favorable time for the sampling is the eighth day, so about three days after symptom onset. And that the Tests themselves fail, then still relatively common. One reason could be that the smear was not done carefully enough. It is also possible that some people wear only a few viruses in the nose and throat. In the case of possibly repeated Testing would provide no better information.

The authors warn, infections solely on the basis of a negative result is completely ruled out. This applies particularly when an infection is likely, because the Patient had contact with Infected or it is already typical symptoms. And also medical employees that can transmit the pathogen easily to the most vulnerable people, should be interpreted as the result of the test to be particularly careful. How high is the error rate in the case of a positive result, was not examined in the study. To date, it is estimated that false alarms are extremely rare. Other corona viruses, the test according to current knowledge, not knocking out

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