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FactCheck: Did the creator of PCR tests say they don't work for Covid-19?

Posts on social media have wrongly claimed that PCR testing is inaccurate and produces a high rate of false positive results.

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CLAIMS SHARED ON social media have suggested that the scientist who created PCR testing, a method used internationally to detect Covid-19, said that the tests could not be used to accurately identify Covid-19 and viruses like it.

Additionally, many of these posts have claimed that PCR testing returns a high number of false positives in a way that has inaccurately inflated the number of people diagnosed with Covid-19. 

The claims first emerged months ago in other countries and have surfaced in Ireland in recent weeks.

The Claim

There are a few variants on the claim, but all of them make some reference to Kary Mullis, the American biochemist who created the PCR test, and suggest that he said the tests were not suitable for testing for viruses or Covid-19.

PCR tests are used in Ireland and many other countries, and involve taking a swab from someone’s throat and nose and then using PCR – polymerase chain reaction – to detect the genetic material of the virus that causes Covid-19. 

A virus is a “small collection of genetic code, either DNA or RNA, surrounded by a protein coat”.

Viruses, which are unable to replicate alone, infect other cells and use components of the host cell to make copies of themselves, which is how they increase in number.

Different versions of the claim suggest that Mullis said that PCR tests:

  • Could be used to find “anything in anybody”
  • Should not be used to test for viruses or infectious diseases
  • Should not be used to test for Covid-19

A Facebook post making the claim in Ireland shared on 14 October, for example,  attributed the following quote to Mullis, who the post describes as the “PCR Covid (fake) test inventor”:

“With PCR if you can do it well you can find almost anything in anybody.”

An image in the post includes another quote that it attributes to Mullis: “PCR test cannot accurately test for infectious diseases… Test cannot detect free infectious viruses.”

The post then says: “This is the ‘test’ that is being used to produce the ‘cases’ to justify fascistic lockdown by finding anything in anybody – and they know it.”

The post has been shared 111 times and received 134 likes and 43 comments.

Another Facebook post, which has been shared 104 times, said that Mullins was the “inventor of the PCR Covid test” and that it was “not made to detect any kind of infectious disease. It’s just there to pick up a signature of your DNA and RNA”.

A post shared on a Facebook page on 24 November, which has been viewed over 15,000 times, said:

The people behind this plandemic knew that to maintain the constant fear they got to keep the cases high, so they decided to use the PCR test, “Kary Mullis” himself stated it can’t be used to detect covid19 and will test positive for anything if you increase its test frequency.

The claims have been made in multiple countries in different languages.

In Ireland, Mullis’ alleged doubts on the tests’ accuracy have been used in claims that the tests used by the HSE to detect Covid-19 are unreliable and overwhelmingly return false positives.

A leaflet with a number of false claims distributed in recent days to some houses in Dublin has referenced Mullis in claiming that there are huge numbers of false positives.

Leaflet false claim PCR

Amplification cycles

Several Facebook posts have suggested that PCR test in Ireland are using too many amplification cycles and that test results are inaccurate as a result.

Amplification cycles are used in PCR testing to replicate genetic material, which is tiny, in order to study it and detect the presence of the genetic material of a virus – in this case, Sars-CoV-2.

One post, which has been shared 250 times, said: “Scary stuff. HSE says the PCR tests use 40-45 amplification cycles. That means it’s totally unreliable and false positives will be off the charts. Could be a dose you had months ago. I think up to 30 is max. recommended. No wonder we have a Casedemic. The inventor of PCR, Kary Mullis said basically anything could be detected if amplified enough.”

Another post referencing amplification cycles, which has attached a photo of Kary Mullis, said that the test in Ireland is “amplified way too much to give accurate readings” and that “20 is the max cycle for accuracy”.

The Evidence

Kary Mullis

Kary Mullis was a biochemist from the US who won the Nobel Prize in Chemistry in 1993 for inventing the polymerase chain reaction (PCR) technique for analysing DNA.

He did not say that the PCR method wouldn’t work for Covid-19 infections or that PCR testing does not work. Comments attributed to him in these claims on social media were either not made by him or have been taken out of context. 

Mullis died last year before Covid-19 was identified, and as such, could not have made any specific assertion about the use of PCR testing for Covid-19.

Claims that Mullis said PCR tests don’t work have already been debunked by the Australian Associated Press back in July, and again by Full Fact in October and Reuters in November.

Mullis did actually say the words “anything in anybody” – but his quote has been taken out of context and presented in a misleading way by claims on social media.

The line comes from a discussion panel Mullis spoke at in 1993, a clip from which has been shared widely on social media pages making false claims about Covid-19 or the effectiveness of PCR testing, such as this one.

Specifically discussing the experience of people with HIV, Mullis said that “someone with HIV generally is going to have almost anything that you can test for”.

“If you have it, there’s a good chance you’ve also got a lot of other ones,” Mullis said, so “to test for that one and say that has any special meaning is what I think is the problem, not that PCR has been misused.”

He said: “If they could find this virus in you at all, with PCR, if you do it well, you can find almost anything in anybody, it starts making you believe in the Buddhist notion that everything is contained in everything else.”

The claims on social media have left out that Mullis was specifically discussing HIV and the experience of people with HIV who also contract other viruses. 

Moreover, Mullis’ views on HIV and AIDS have been widely discredited. Mullis was a proponent of a theory led by a scientist called Peter Duesberg, first published in 1987, that HIV was not the cause of AIDS – it is.

The other quote that has been attributed to Mullis in these posts – that PCR testing “cannot detect free infectious viruses” – actually comes from an article written by an American writer called John Lauritsen. Mullis did not say it. 

In the article, Lauritsen wrote about how tests like PCR don’t count the number of viruses in the blood. Instead, the test detects the genetic material of the virus to determine whether the virus is present.

This does not mean, and he is not saying, that PCR tests are not suited to testing for whether a person has contracted a particular virus, such as Covid-19.

Kary Mullis, who was born in 1944, died on 7 August 2019. 

The first cases of Covid-19 were reported by officials in December 2019 in Wuhan, China.

Mullis could not have made any specific commentary on the effectiveness of using PCR testing for Covid-19.

Mullis received the Nobel Prize in Chemistry in 1993 for his invention of the PCR testing technique.

Presenting the award, Professor Carl-Ivar Brändén of the Royal Swedish Academy of Sciences said that the PCR method had a “profound influence on basic research in biology”.

“In addition to being an indispensable research tool in drug design, the PCR method is now used in the diagnosis of viral and bacterial infections,” Brändén said.

In an interview in 2005, Mullis said: “There’s nothing like getting a Nobel Prize. But by 1993, I didn’t need any confirmation that this was a useful thing because it was already.”

“You couldn’t find an issue of Science or Nature or Cell or PNAS that didn’t have lots of people using PCR.”

PCR testing and Ireland

The PCR testing method is being used internationally, including in Ireland, to detect if a person is currently infected with Covid-19.

The RT-PCR test is considered the gold standard for diagnosing a suspected case of Covid-19, and is the test recommended by the European Centre for Disease Prevention and Control and the World Health Organisation.

Speaking to, a spokesperson for the HSE said Ireland’s use of the PCR testing technique is “based on expert advice”.

The method works by amplifying DNA so that it can be closely studied and used to detect the presence of a virus.

Claims about PCR tests in Ireland have said that they are inaccurate or cause a high volume of spurious false positives because the HSE uses 40-45 amplification cycles, which the posters say are too many.

Speaking on TheJournal.ies The Explainer podcast, Professor Philip Nolan said that there is no evidence the tests are producing high numbers of false positives or that the amplification cycles are producing inaccurate results.  

“The virus is tiny, it’s little fragments of genetic material, and what the PCR test is doing is replicating any genetic material it finds in the sample, and that’s amplifying the amount of virus,” Professor Nolan said.

“[That] every cycle is replicating genetic material and doubling its amount is a simple way to think about it,” he said.

“The cycle threshold is the number of times you have to amplify the DNA to detect the presence of genetic material associated with Sars-CoV-2.

“The more amplifying you have to do, the more cycles you have to do; that suggests there was less of the virus in the original sample,” he said.

“A low cycle threshold suggests there was lots of virus, the person might be very infectious, and a high cycle threshold suggests that there’s less of the virus and either someone is very early on in their infection, so they’re shedding very little of the virus yet but they’ll go on in the next day or two to become quite infectious, or they’re at the end [of their infection].”

Professor Nolan said that a high cycle threshold “doesn’t necessarily cast the test into any doubt”.

“The virus is still there and one of the reasons there may be very little virus is that you could have taken a bad sample – that the person has plenty of virus, but you didn’t put the swab far enough back in their nose to pick it out, so you only got a small sample of the virus even though your patient has lots of it.

“There’s lots of reasons why you might have a low level of virus in your sample, and none of those reduce your concern about the person.

They may still be very sick, they may be about to get very sick, they may be recovering but may have infected people before you took the sample, so you have to treat that seriously.”

Professor Nolan said that in cases where there may be concern that something is wrong with a test or that it is taking a long time to amplify the virus, “you simply do another test”.

“There is no evidence that we’re detecting the virus in people who are not really infected – viral fragments from months ago or somebody strangely having some Sars-coronavirus nucleic acid up their nose but not really being infected: they are simply not real issues.”

He said that there “isn’t one cycle threshold – 30, for instance – that if you exceed it, it means your test isn’t really positive”.

“Different manufacturers have different recommendations for what kind of cycle threshold you might become suspicious and think about the clinical context or think about repeating the test,” he said.

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Health Feedback, a network of scientists that review scientific claims for accuracy, has debunked the false claim that a sensitive PCR test can drive inflated numbers of recorded Covid-19 cases.

Additionally, has already debunked false claims that the HSE said its testing method was useless – it did not.

Dr Cillian de Gascun, the director of the National Viral Reference Laboratory (NVRL), told that it is “the most accurate test we have, the most sensitive test we have and the most specific test we have”. 

Dr de Gascun said that the PCR testing method is widely used in diagnostic laboratories and has been in use for years, such as in testing for herpes, HIV, and hepatitis C. 

Speaking on Newstalk, de Gascun said that at most, the testing system in Ireland produces a maximum of one false positive for every 500 tests carried out, and likely even fewer than that in practice.

In the UK, the BBC has also countered claims around false positives and the accuracy of tests.

The Verdict

PCR testing is effective at testing for Covid-19 and other viruses, and is widely considered to be the gold standard for virus testing.

The method does not result in an abundance of false positives, and a PCR test for Covid-19 will not simply detect “anything” in an individual.

Claims on social media have either incorrectly or misleadingly – depending on the claim – attributed quotes to the creator of PCR testing, Kary Mullis, that suggest he was opposed to using PCR tests to test for viruses like Covid-19.

Of the two “quotes” attributed to him most frequently in these claims, one of them was taken out of context in a misleading way, and another was not said by Mullis but by a writer and has also been misinterpreted.

Mullis died before the first cases of Covid-19 were reported, and could not have commented specifically on the effectiveness of PCR testing for Covid-19.

As a result, we rate the claim that the creator of PCR tests said they do not work for Covid-19: FALSE.

As per our verdict guide, this means: The claim is inaccurate.’s FactCheck is a signatory to the International Fact-Checking Network’s Code of Principles. You can read it here. For information on how FactCheck works, what the verdicts mean, and how you can take part, check out our Reader’s Guide here. You can read about the team of editors and reporters who work on the factchecks here.

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