Covid: Fizzy drinks and tap water give false positives on lateral tests

Children were found to be using this method to get out of school when daily testing was compulsory.

As the government plans to scrap free lateral flow tests from April 1, except for over 75s and people with weakened immune system, it might still interest you to know that people have discovered dubious ways to get false positives using LFTs.

Dubious Ingenuity?

Dr Karan Rangarajan, a doctor with the NHS who also creates content on TikTok, said fizzy drinks, fruit juice and tap water are giving false positive lateral flow antigen test results. Known as Dr Rajan on TikTok, the medic took to the platform to explain what this happens.

In a video that has received more than six and a half million views, he could be seen dropping water on the LFT and soon after, revealing a positive result. Dr Rajan, known for busting health myths on the platform, explained in the now-viral video:

First we need to look inside the lateral flow device. This grey box and the portion just above it contain antibodies that are sensitive to the Covid-19 virus. If you use things like soda, tap water and fizzy drinks, that's going to provide an altered pH, which will affect the function of the antibodies on the test line.

Read more:

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Feeding into conspiracy theories

He added that if people do not follow the manufacturer’s instructions when using the test kit, they might get inaccurate results. Dr Rajan continued:

That is why you need to use this buffer solution (consisting of 99.7 percent saline solution) which provides a stable pH that will actually make the test work.

Conspiracy theorists have used these findings to argue that the pandemic is a hoax or that there are fewer cases than being reported.

In 2021, the BBC also reported that some school children were using this method to arrive at false positives in order to get out of school.

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