In viral video, doctor shares how antigen test can show false positive due to water, soda

In the era of COVID-19, as many types spread around the world, at-home testing has become a saving grace for many individuals and families still battling the virus.


two main tests Known for most includes antigen testing and PCR.

PCR, or molecular tests, has been cited as the “gold standard” when testing for COVID-19 due to the test’s nearly 100 percent accuracy and sensitivity. This involves taking a sample of nasal swabs or saliva and treating it with an enzyme that converts RNA into double-stranded DNA, eventually creating two copies of coronavirus DNA from the original one piece of RNA.


The downside to PCR is that it requires skilled technicians to oversee the testing process, which makes antigen tests more efficient when time is of the essence. While overall less accurate than PCR, these tests can be done at home and offer convenience while keeping some extra money in your pocket.

Rapid COVID-19 tests, also known as lateral flow tests, are done at home and show positive and negative coronavirus results. This photo was taken in England in December 2021.
Matt Cardi / Getty

Antigens are described as substances that cause the body to produce an immune response, therefore triggering a generation of antibodies. Antigen tests are treated with a liquid containing salt and soap that breaks down cells and other particles and then applied to a test strip.


Meanwhile, the Federal Trade Commission recently warned that fake home tests are being sold online. If it is not authorized by the Food and Drug Administration, it is not a viable test.

However, if antigen tests are being obtained at home and used by individuals in their own homes, there can certainly be user error associated with the test results. The same message was sent by Dr. Karan Raj on his popular Tiktok page.

He posted a video in response to a man whose rapid test came back positive after being splashed with tap water. The first thing it does is open the test, also known as a lateral flow device.


“This gray box and the part just above it contain antibodies that are sensitive to the COVID-19 virus,” Raj said. “If you use things like soda, tap water, and fizzy drinks, it’s going to provide an altered pH that will affect the function of antibodies on the test line.”

Raj said that “a buffer solution is necessary to provide a core pH that will actually serve as a test.”

The video, which has garnered over 6 million views, draws some clear conclusions. At first, many commented on the fact that the directions should be followed for the best possible result – ironically ridiculed by those who got weird results because they didn’t read the packaging.


Even the American Society for Microbiology wrote in November that “a team of Canadian researchers has shown that rapid antigen tests for SARS-CoV-2 only work when the manufacturer’s instructions are followed.”

Dr. Jason J. LeBlanc said the impetus for such a study was to demonstrate a “pretty clear” view of the amount of false-positive tests being virally caused by soda or fruit, etc.

LeBlanc said, “Seeing the misuse and misrepresentation of the test function on social media, we felt compelled to seek robust scientific data to explain the formation of false-positive results during SARS-CoV-2 antigen testing. “

In response to questions about the test material, the makers of CLINITEST, one of the rapid antigen tests on the market, said that its buffer solution contains 99.7 percent saline solution.

Some commented on Raj’s video, serious or not, saying that false-positive tests could help kick him out of school or work for being “contagious.”

“The amount of time I am taking out of school because of this video is going to be crazy,” said one TikToker.