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“In Austria, even a glass of Coca-Cola is positive for the rapid coronavirus test,” say social media posts with a video in which an Austrian MP has an experiment that gives a positive result. Thus, the protagonist of the scene and thousands of users who share it in several languages ensure that the tests used throughout the world during the pandemic are useless. In fact, the manufacturers of the diagnostic kit and various experts explained to AFP that the experiment only reflects that the results of such tests are not valid if they are not used in the right conditions.
The video, which is approximately 3 and a half minutes long, has been shared more than 6,000 times on Facebook (1, 2 and 3), Instagram, YouTube (1, 2) and Twitter (1 and 2) since the last day. December 11. It was also published in articles (1, 2) shared hundreds of times, according to the CrowdTangle tool.
It shows Austrian MP Michael Schnedlitz, who conducted the experiment with an antigen test and a cola drink during his speech on December 10. “At the end of my speech, you will see how useless and misleading this test is”said the politician, who showed a glass of the drink and the diagnostic test deposited in the liquid. Minutes later, Schnedlitz assured that the test result was positive and accused the government of raising taxes on citizens with the purchase of these tests.
Screenshot taken on December 23, 2020 from a Facebook post (Screenshot taken on December 23, 2020 from a Facebook post)The same video circulates in publications in Italian, German, English and Spanish.
The AFP control team has already seen similar videos: those who tried juice, checked in Spanish and apple puree as a sample also had positive results.
In all cases, both the kit manufacturers and the different experts consulted indicate that the experiments were carried out under incorrect conditions, invalidating the results obtained.
Antigen tests
The tests for covid-19 available around the world can be divided into three categories. The first includes PCR tests (Polymerase Chain Reaction, “polymerase chainreaction”), carried out through a biochemical process, in which it is analyzed whether a very specific part of the new coronavirus genome is present in the sample used (result positive). The Robert Koch Institute (RKI) calls this test, used by laboratories around the world, “Golden pattern” for the diagnostic.
The second is that of serological tests, which check if a person has antibodies to SARS-CoV-2 in the blood. Scientists use this method to calculate how many people have had an infection.
Finally, antigen tests, like the one used in the video, are less accurate than PCR tests, but provide faster results. They are also less sensitive than PCR and require a higher viral load to show a positive result. This means that, especially if the infection is recent, the antigen test can give false negatives.
PCR detects the genetic material of the new coronavirus, while antigen test They are designed to identify the molecules that surround the virus.
In September, the Federal University of Rio de Janeiro (UFRJ) gave its approval to the antigen tests, showing that they would be an alternative to PCR and could help contain the advance of the pandemic. However, in its guide updated in December, the US Centers for Disease Control (CDC) cautioned that antigen tests are less sensitive than CRP.
Asked about the video in which apple juice was used as a sample for an antigen test, Juan Sabatté, doctor, doctor in Microbiology and researcher at the National Council for Scientific and Technical Research of Argentina (Conicet) told AFP that “These tests usually detect components of the SARS-COV-2 virus using specific antibodies”. When detected, a reaction is generated that is visualized with colors and “in the form of a band (the line that appears if it is positive)”.
The manufacturer’s explanation
The test that Schnedlitz used is produced by Dialab GmbH. After the video went viral, the company posted an explanation on its Facebook account, stating that the legislator did the test incorrectly.
First of all, it is noteworthy that the parliamentarian did not prepare the cola drink sample in the buffer (buffer solution), which allows stabilizing the pH values of the substance. Failure to do so, explains the company, causes the destruction of the antibodies contained in the test, which are those that react to the virus. This procedure, indicates the company, “Makes the positive brand visible”.
“If the test had been carried out correctly, as indicated in the product insert, it would have been negative”said the statement. As evidence, the publication includes a video in which a person performs the same experiment, but mixing the cola drink with the buffer solution. The result obtained after a few minutes is negative.
“These examinations should always be performed by health professionals or trained, to avoid this type of result”added the text.
The user manual for these kits indicates that 10 drops must be removed from the sample. mixed with the buffer solution for later use in the screening test.
Screenshot taken on December 17, 2020 of the brochure published by Dialab GmbH
When asked about the Schnedlitz experience, a spokesperson for Dialab GmbH told the German press group Welt that “Any pregnancy test would have been positive. Before making these embarrassing public statements, you should know a little about chemistry. “.
In the right conditions
The immunology and biochemistry experts consulted by AFP also pointed out that the conditions under which antigen tests are performed, particularly the acidity level, are crucial for a valid result. In addition, they highlighted that the tests are manufactured only to be carried out with the samples for which they were evaluated.
“It is not an achievement to distort the test conditions to the point of giving false results”Thomas Decker, a professor of immunobiology at the University of Vienna, told AFP. “The test was developed to allow an antibody to bind to antigens, not to react to certain foods”, he clarified.
The specialist was forceful and compared the viralized experiment in the networks with the statement that “a car no longer works if you put applesauce in the tank [de gasolina]“.
Along the same lines, Anette Beck-Sickinger, a professor of biochemistry at the University of Leipzig, Germany, stated that this test, like any biochemical process, “it can only work if done under the right conditions”.
Modifying test conditions, such as pH or temperature, can “cause a nonspecific antibody reaction”, causing a false positive, explained the expert. In other words, an incorrect application of the test shows incorrect results.
In conclusion, the experiment with a cola-based drink carried out by the Austrian legislator does not prove that the antigen test is useless in detecting covid-19. Both the kit manufacturer and the experts consulted indicated that the results are invalid because the test was performed incorrectly.
