A stunt that recently went viral on TikTok, inspiring a multitude of "how-to" videos, has landed a teen in hot water after he shared a tip on how to get a COVID-19 lateral flow test give you a false positive. The "hoodwinking" approach actually just involves disrupting the test by putting incompatible liquids into the drop tester and has gained much in the way of negative press owing to the fact that there are a small number of alleged cases of students using it to stay home from school.
While several substances – including lemon juice, Coca-Cola, and ketchup – have been found capable of producing a false positive in the lateral flow drop test, that this happens isn’t an indicator of the test’s efficacy in detecting the virus. Lateral flow testing kits are supplied with a specific solution for transferring biological materials from the swab to the test. This liquid is specifically designed to filter through the test and react with its ingredients to give a positive, negative, or inconclusive result. Using any other liquid therefore has the potential to influence the result in disrupting the test’s normal function.
While certain liquids are able to influence a positive result in the lateral flow test, they're not technically a false positive result. A false positive only applies when the correct steps are followed for any given medical test and the result of positive is later found to be false. In using innapropriate solutions on the COVID lateral test kit, you effectively break it and so the positive result is simply a reflection of the kit's improper use.
“If someone deliberately mucks up the protocol then of course you’ll get a duff result," Professor Andrea Sella of University College London told the Guardian. "But I would add that it’s not a ‘false positive’ in the true sense. Because false positives are ones that take place in spite of adherence to the protocol.”
In a recent interview with The i, the British teenager expressed that the quest for a positive result wasn’t intended to be used as a weapon of mass disruption. ““I’m not a serious person – the idea wasn’t to get a positive test, it was just to play around,” he said. “The videos are just kids having fun at the end of the day, I was bored and I found it fun, I liked doing it. I want to try something that no one’s tried – maybe I’ll make a new one soon.”
The UK is currently operating under a monitoring system which sees students and teachers taking two lateral flow tests per week in the hopes of identifying small numbers of cases before they have the potential to cause an outbreak in school. A string of false positives therefore has the potential to cause much disruption as students may be sent home to contain an outbreak that isn’t actually happening. In a year following extensive lockdowns that saw some parents go without adequate childcare support increasing inequalities, the need for schools to return to service as near-normal as possible spreads well beyond the direct effect it has on the education of its students.
While the test-wasting trick has received much attention in the media, actual reports of it having been wielded against schools appear low though it’s possible false positives are being used without school’s knowledge. As such, if the trend is actually being used in the way it’s reported to be remains unclear but it’s one that undeniably and needlessly wastes lateral flow tests. The takeaway: put down the lemons, TikTok.