PCR tests are not ‘a fraud’

13 August 2021
What was claimed

Kary B Mullis, inventor of PCR tests, said they cannot detect free infectious viruses.

Our verdict

This quote does not come from Mullis himself, but from an article about him. PCR tests accurately detect particular viral genetic material, such as genetic material of the virus that causes Covid-19, rather than testing directly for infectivity.

A Facebook post shows a meme with a picture of Kary B Mullis and the text: “Covid test a fraud?” 

It goes on to say “These PCR tests cannot detect free infectious viruses” and seems to attribute the quote to Dr Mullis, who it calls “laureate & inventor of the PCR test”. Text in red then highlights that he died in August 2019. 

Dr Mullis was the inventor of PCR tests, and did die in August 2019, well before the start of the Covid-19 pandemic. It’s therefore unlikely that he had qualms about the tests used to detect Covid-19 specifically. 

As we have written previously, there seems to be confusion over quotes attributed to him in a 1996 article about HIV and AIDS.  

A passage by the author of the article (which is not a quote from Dr Mullis) says “these tests cannot detect free, infectious viruses at all”. This section of the article however, is talking about the use of PCR testing to assess viral load (the amount of virus present) in people with HIV. The author of the article quotes Dr Mullis as saying “Quantitative PCR is an oxymoron”, but again, this is in the context of measuring viral load in HIV patients.

This doesn’t mean that PCR testing doesn’t work at all, but because PCR tests look for viral genetic material, there are limitations in using it to detect the specific levels of virus or to measure infectivity. For example, PCR tests can detect whether someone is or has recently been infected with Covid-19, by detecting the presence of particular parts of SARS-CoV-2 viral genetic material. Many of these results will indicate an infectious case, however, because the presence of viral material can persist for some time after infection, a positive PCR test may not always indicate ongoing infectivity. 

PCR is the gold standard test for SARS-CoV-2 as mandated by the World Health Organisation and Public Health England. Like all tests, there are some false negatives and false positive results associated with PCR testing, however overall it is thought to be very effective. We have previously written about how PCR tests work, and how effective they are.

This article is part of our work fact checking potentially false pictures, videos and stories on Facebook. You can read more about this—and find out how to report Facebook content—here. For the purposes of that scheme, we’ve rated this claim as partly false because PCR tests are not fraudulent and this quote appears to be misattributed.

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