Vaccinated, tested and still infected: how reliable are Corona rapid tests?

They felt safe, vaccinated and tested. The antigen rapid tests from the trade were all negative. But shortly after a private meeting with friends came the evil surprise: ten of the 20 present had become infected with the coronavirus.

This is how a Twitter user described his experience. The symptoms were different-from high fever to loss of taste and smell to cold symptoms or none at all.

For virologist Christian Drosten, this is not an isolated case, but an indication that corona rapid tests are only limited in significance. He shared the person & APOs; s tweet and expressed doubts about the 3G rule that grants vaccinated, genesis and tested access to facilities or events. "before symptoms start, rapid tests are simply not sensitive enough. Therefore my doubts about 3G, "he wrote on Twitter.

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On Friday, the Federal Council voted in favour of the infection Protection Act presented by the SPD, the Greens and the FDP. This means 3G in the workplace, in buses and trains. In addition, vaccinated and genesene may only have a negative test result in certain events or institutions (2G plus) in accordance with the decisions of the Federal Government with the Länder under certain circumstances, which are based on the burden of the clinics.

Also in the private environment, the antigen rapid tests are again more used to protect themselves and others from infections. In drugstores, the test was temporarily out of print.

& quot; since September, we have seen a continuous increase in demand for Corona self-testing, & quot; said the DPA & APOs; s drugstore chain Rossmann. "availability is guaranteed in principle, but short-term bottlenecks may arise due to the current high demand."

[read also: "they have a shot": Meissen became a Corona hotspot (T +)]

Even with the competitor DM, a speaker explained, it could happen that self-tests are temporarily sold out. However, the markets would be regularly supplied with new products.

Tests differ greatly in quality

But how reliable are the rapid tests from the trade? The Paul-Ehrlich-Institut has investigated a total of 122 COVID-19 antigen rapid tests for their sensitivity. The study concludes that the tests are very different in quality: "96 antigen rapid tests met the required criteria, partly with very good results, 26 tests did not provide the required sensitivity."

According to the study, sensitivity is considered to be a minimum of 75 percent. This sensitivity describes the ability of the test to correctly detect the virus in the sample.

It is problematic that manufacturers can certify their tests themselves so far, according to the study. This is not supposed to change until May 2022. Then the tests must be examined by an independent institute before they enter the market.

How useful are rapid tests for vaccinated people?

The virologist Christian Drosten, who was also involved in the study, also points out that the sensitivity of the rapid tests appears to be worse in vaccinated patients than in unvaccinated patients.

"in my preliminary assessment, it looks as if infections in vaccinated patients are not as well demonstrated by the antigen rapid test, especially in the first days of the infection. Unfortunately, however, the study situation is not yet sufficient, "he said to the" Bild "newspaper.

[read also: unvaccinated midwife infects mother and child during birth (T +)]

Andreas Bobrowski, chairman of the professional association of German laboratory physicians, said to the "Bild" newspaper that the PCR test was clearly superior to the antigen rapid test, especially in asymptomatic patients. "here, the significantly lower sensitivity of an antigen rapid test is a problem."

The exponential increase had to be stopped quickly, the Chancellor demanded. Virologist Drosten recommends "closing vaccination gaps, booster and reducing contacts by then."