Kids: They’ll do anything to cut school — even by faking a positive COVID test with their favorite soda.
Yes, you read that right. Kids have taken their mischief to the next level in the most opportunistic way the pandemic affords, and it’s exposing one unique flaw among COVID lateral flow tests (LFTs).
According to BBC, the trick began circulating on TikTok in December and has since prompted a Liverpool, England, school to warn parents that their children might test the scheme for themselves.
The process involves only a few drops of soda and an LFT device (which, according to the source, contains three elements: “a strip of paper-like material, called nitrocellulose, and a small red pad, hidden under the plastic casing below the T-line”).
You can opt for orange juice as well, if you’re following along with BBC reporter Mark Lorch’s examples.
The red pad included in the LFT device contains gold nanoparticles — which actually appear red — that “allow us to see where the antibodies are on the device” and, of course, the pad also includes antibodies that bind to the COVID-19 virus, if present.
To begin, mix the liquid buffer solution with your sample — a few drops of soda or orange juice if you’re trying to achieve a false positive, as we are.
If you’ve ever used a home DNA kit, you might be familiar with the science behind buffer solutions or, at least, with how they’re used. But for those who don’t know, buffer solutions aim to keep your sample at an optimum pH before you drop it onto the papery strip provided with the kit (or, in the case of DNA kits, insert your sample into a tube).
How would this react with something as acidic as soda or orange juice?
First, let’s discuss how it reacts to an actual COVID-positive sample.
“The fluid wicks up the nitrocellulose strip and picks up the gold and antibodies. The latter also bind to the virus, if present,” Lorch’s report says.
“Further up the strip, next to the T (for test), are more antibodies that bind the virus. But these antibodies are not free to move – they are stuck to the nitrocellulose. As the red smear of gold-labelled antibodies pass this second set of antibodies, these also grab hold of the virus. The virus is then bound to both sets of antibodies – leaving everything, including the gold, immobilised on a line next to the T on the device, indicating a positive test.”
Any remaining gold antibodies not bound to the COVID virus move upward to the control group — a third antibody set that doesn’t pick up the virus. It’s important to note this line is marked with a “C” for “control.”
According to the report, this final line verifies that the test was performed successfully.
But back to our favorite sugary drinks.
The science behind the false positives the drinks produce isn’t clear, but it likely can be chalked up to the acid’s abilities to alter the antibodies’ function, according to the BBC story.
Antibodies don’t have an affinity for many things — and the source tells us that soda likely isn’t one of them.
One of the commonalities between sodas and orange juice is the presence of citric acid — which means these beverages would maintain low pH levels that could clash with the closer-to-neutral pH of antibodies.
Since the sole purpose of the liquid buffer we mentioned earlier is to ensure the sample’s pH remains balanced, of course the presence of highly acidic beverages would wreak havoc on the results.
But the BBC article notes one easy way to bypass this new school-skipping trick:
“I tried washing a test that had been dripped with cola with buffer solution, and sure enough the immobilised antibodies at the T-line regained normal function and released the gold particles, revealing the true negative result on the test,” Lorch wrote.
So it’s an easy way to ensure there is no juvenile scheming going on with these at-home tests.
Sorry to burst your bubble, kids.
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