A video circulated widely on social networks in early December, claiming to demonstrate that antigen tests are not effective in detecting Covid-19. We see an unusual experience: a test carried out on… applesauce, which turned out to be positive. Many internet users concluded that the test was unreliable and that the number of cases was exaggerated. But these conclusions are hasty, since the test in question meets the criteria for effectiveness in detecting the virus in humans, the only “carrier” of the relevant virus in the context of a pandemic.
The video is 2’15 long and has been viewed hundreds of thousands of times on Facebook, Twitter, Telegram, and Instagram since December 8. Internet users who relay it claim that it shows “an apple sauce positive for Covid-19” according to a Covid-19 test earlier with a PCR test [test de référence, NDLR], sometimes an antigen test – newer, faster and tried less reliable by the French health authorities.
“The applesauce tested positive during the test,” this Facebook user commented above on December 8. It is the oldest video occurrence that we have been able to find, it has collected over 200,000 views.
Is the test really positive?
By watching the video carefully, we see that it is made up of several elements mounted one after the other.
The first element shows a person wearing gloves using medical equipment from the MEDsan brand, the name of a German start-up manufacturing different tests. On its website, there is a list of the tests proposed, including the antigen test used for this experiment.
This antigen test works like this: the extracted substance must be diluted in a liquid and placed on a swab. The latter will present different combinations of colored lines depending on the result. The whole procedure is detailed in a multilingual notice and an video on the MEDsan website.
These two documents clearly indicate that the test must have lines facing the letters C and T to be positive. Many Internet users therefore reacted to the video, which at first glance shows a single line in front of the letter C, which corresponds to a negative result.
Other Internet users responded that a very light line seemed to appear opposite the letter T, which could then correspond to a positive result, since the manufacturer indicates in its instructions that a “light or weak test line should be interpreted as a positive result”.
This very light line only appears in the last two clips of the timeline, a video clip that follows the first after a cut, then a photo. The filmed test pattern is the same in each sequence, but it is possible that the test was replaced by a different one at the time of the cuts in the video. Not being able to verify this independently, we assume that each sequence shows the applesauce test well.
Contacted by our editorial staff, MEDsan confirmed that the visible result at these two places shows “a positive result”. The presence of a line at the level of T, even extremely weak, clearly indicates a positive result for Covid-19.
In the photo above, transmitted to our editorial staff by the manufacturer, we can see a series of positive results carried out on humans with varying degrees of intensity of the result lines. The bottom two results roughly match what we see at the end of the video broadcast on social media.
Does this test indicate that applesauce is indeed a carrier of Covid-19?
Antigenic tests have been designed and manufactured to detect the virus in humans, from samples taken from the nasal passage or sometimes from the mouth with a swab. They are not calibrated to absorb other types of substances, which can “mess up” them and give false positive or false negative results.
Asked by our colleagues from AFP Factuel, the manufacturer MEDsan had other “irrelevant” materials tested: cherry jam, alcohol-based disinfectant, apple juice, apple juice and window cleaner. For the cherry jam and the disinfectant, the result was positive.
Several elements can explain it according to two university researchers interviewed by AFP, in particular the acidity rate. The pH of the collected sample is normally neutralized in a buffer solution supplied with the test. However, according to professor of biochemistry Annette Beck-Sickinger, this buffer solution is not calibrated “to neutralize very acidic foods such as apples or mangoes”.
To sum up, Professor Thomas Decker gives a metaphor: “The test was developed so that antibodies and antigens combine under certain conditions, conditions which do not take into account the presence of food. It’s like laughing at the fact that a car can no longer drive when you fill your tank with applesauce ”.
Impossible to say if the compote contains Covid-19
In conclusion, we cannot know if the applesauce in question carried traces of the virus or if it “out of whack” the test by its level of acidity, sugar, or other. However, according to several researchers specializing in the subject cited by AFP, the conditions of the test and more particularly the nature of the element tested do not allow a reliable result to be obtained, much less to draw conclusions on the effectiveness. of this test on humans.
Hasty conclusions drawn for political ends
Because this video has been widely relayed and extrapolated to serve a political agenda. We thus notice a catchy music, texts and stickers with a sarcastic tone, but especially the German language, which gives us an indication of its origin.
In Germany, faced with a sharp increase in the number of cases and deaths during the second wave of the epidemic, the government decided at the end of November to extend restrictions, then harden them December 13. An unpopular decision among a part of the population and the political class which questions the reliability of these figures and therefore of the tests.
At the head of this movement of mistrust of vaccines and social distancing measures is the far-right party AfD (Alternative for Germany). A youth section of the party posted a meme on Twitter and Instagram [montage photo humoristique, NDLR] making fun of “quick tests” and using an image of applesauce.
The video was also widely circulated via Telegram channels, an encrypted instant messaging application. These chains, like “NRW News” or “Wake uppro-Trump, anti-vaccine and conspiracy messages in German are sent to hundreds of subscribers.
A similar experiment, this time carried out on Coca-Cola, was even presented to the Austrian Parliament by Michael schnedlitz, member of the far-right movement FPÖ. He argued that the tests were “worthless” and that the government had implemented a form of “light dictatorship” during the Covid-19 pandemic.
The manufacturer of the test in question, Dialab, pointed out a flaw in the procedure and demonstrated on its Facebook page that the result would be negative if all the steps were followed correctly.
In the caption of this video, the manufacturer explains that the deputy did not mix the Coca-Cola with the buffer solution to neutralize its very high acidity. This acidity therefore “destroyed the antibody proteins contained in the test”, rendering the result positive. According to the manufacturer, this false positive result “would have been the same with any other similar test from another manufacturer”. In his counter-experiment, an employee of the manufacturer mixes soda well with the buffer solution and the result is negative. “Such tests should always be performed by hospital personnel or trained to avoid such results and presentations,” concludes the manufacturer.