Children are using soft drinks to fake covid-19 positive tests – ZAP

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Tiago petinga / Lusa

Children are using soft drinks to fake covid-19 tests. The acidity of the juices affects the effectiveness of the tests, showing a negative result.

Children will always find cunning ways to skip school, and the last trick is fake a positive covid-19 test using soft drinks. So how is it that fruit juices, soft drinks and dishonest children are misleading the tests and is there a way to differentiate a false positive result from a true one? An investigator looked for the answer.

First, it opened Coke bottles and orange juice and placed a few drops directly in the lateral flow tests (LFT), rapid antigen tests. A few minutes later, two lines appeared in each test, supposedly indicating the presence of the virus that causes covid-19.

How do soft drinks do this? One possibility is that the drinks contain something that the antibodies recognize and bind to, just as they do with the virus. But that’s pretty unlikely.

The reason antibodies are used in tests like these is that they are extremely picky about what they bind to. With this in mind, they will not react to the ingredients of a soft drink.

A much more likely explanation is that something in the drinks is affecting the functioning of the antibodies. A variety of fluids, from fruit juice to cola, have been used to mislead the tests, but they all have one thing in common — they are highly acidic.

Citric acid in orange juice, phosphoric acid in Coca-Cola and malic acid in apple juice give these drinks a pH between 2.5 and 4. These are very adverse conditions for antibodies, which have evolved to act widely. into the bloodstream, with its nearly neutral pH of about 7.4.

Maintaining an optimal pH for the antibodies is key to the correct functioning of the test, and that is the job of the liquid buffer solution with which you mix your sample, provided with the test. If you mix glue with the solution, the LFTs behave exactly as you would expect: negative for covid-19.

Therefore, without the solution, the antibodies in the test are fully exposed to the acidic pH of the beverages. And that has a dramatic effect on its structure and function.. Antibodies are proteins, which are made up of building blocks of amino acids, linked together to form long linear chains.

These chains fold into very specific structures. Even a small change in chains can have a dramatic impact on how a protein works.