The BMJ didn’t say PCR tests are useless

25 June 2021
What was claimed

A BMJ article is proof that the use of PCR tests are a massive part of the problem.

Our verdict

The BMJ article illustrates some of the concerns around potentially using PCR testing for asymptomatic mass testing. This is not how PCR tests are generally being used in the UK.

A social media post has shared a screenshot of an article in the British Medical Journal (BMJ) about PCR testing, and says “how much more proof do you want that tests are a massive part of the problem”. 

PCR tests are one type of test for Covid-19 which detect viral RNA (genetic material) for SARS-CoV-2, and require a swab sample to be taken and then sent to the lab for processing. 

The post uses an extract from the BMJ article from September 2020 to support the claim, however that’s been taken somewhat out of context. The article outlines concerns about the potential for PCR testing being used for mass testing of the population, when that was an aim of so-called operation moonshot. This was a government project which aimed to “deploy mass testing” with the aim of allowing people to “lead more normal lives, and reduce the need for social distancing”. The article goes on to outline that like any test, PCR tests have flaws. They discuss, for example, that PCR tests can detect fragments of viral genetic material for some time after infection. Therefore, some people with a positive test may no longer be infectious but could still be asked to self isolate. The article raises the point that this becomes more likely and widespread if the tests are used for mass testing of asymptomatic people. 

This is not how PCR tests have been used to date. Instead, lateral flow tests have been used for asymptomatic mass testing, with PCR testing mainly being reserved for particular circumstances. PCR tests are used, for example, in people with symptoms of Covid-19, people who have had a positive lateral flow test, individuals who are contacts of people who have tested positive for Covid-19, and sometimes, when sequencing is particularly useful, for surge testing and to facilitate travel. 

The author of the article, Jon Deeks, Professor of Biostatistics at the University of Birmingham, told Full Fact that: “This editorial in the BMJ was written concerning testing people who do not have symptoms, as was proposed in the Moonshot plans, and is currently done with the lateral flow test. The comments in the article about RT-PCR tests related to the problems which would occur should they be used to test people without symptoms, which is not happening. The editorial made it very clear in its very first sentence that the authors regard the PCR test as a useful test for detecting SARS-CoV-2 virus in people with symptoms and do not regard them as a problem. When making statements about the value of a test it is essential that it is done in the context where the application of a test technology is applied.”

We have written more about PCR tests and lateral flow tests for Covid-19 previously. 

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