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PCR testing deemed unreliable by Portuguese Court

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Yew

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It seems that the commonly used PCR test has been deemed unreliable by a court in portugal


The PCR test “is unable to determine, beyond reasonable doubt, that a positive result corresponds, in fact, to the infection of a person by the SARS-CoV-2 virus”, said the Lisbon Court of Appeal.​

While the court has deemed the test to be unreliable, medical experts have hit back against these claims, stating the judges have acted “irresponsibly” in their ruling.

The initial decision, which was made on 11 November, related to an appeal by the Regional Health Administration of the Azores, following a request for habeas corpus - immediate release - of four German citizens who had been forced by the health authority to comply with isolation for 14 days in the hotel room

According to the process: “There is no evidence that this diagnosis was actually carried out by a professional qualified under the Law and who had acted in accordance with good medical practices”. These acts are reserved for the exclusive competence of a doctor.

“The only element that appears in the proven facts is the performance of RT-PCR tests, one of which presented a positive result in relation to one of the applicants”, reads the document.

The judges quoted a paper published in The Lancet by Elena Surkova, Vladyslav Nikolayevskyy and Francis Drobniewski, which stated: “Any diagnostic test result should be interpreted in the context of the pretest probability of disease. For COVID 19, the pretest probability assessment includes symptoms, previous medical history of COVID-19 or presence of antibodies, any potential exposure to COVID-19, and likelihood of an alternative diagnosis. When low pretest probability exists, positive results should be interpreted with caution and a second specimen tested for confirmation.

The paper continues: “Prolonged viral RNA shedding, which is known to last for weeks after recovery, can be a potential reason for positive swab tests in those previously exposed to SARS-CoV-2. However, importantly, no data suggests that detection of low levels of viral RNA by RT-PCR equates with infectivity unless infectious virus particles have been confirmed with laboratory culture based methods.

“To summarise, false-positive COVID-19 swab test results might be increasingly likely in the current epidemiological climate in the UK, with substantial consequences at the personal, health system, and societal levels (panel).”

The judges concluded by stating that: “The problem is that this reliability is shown, in terms of scientific evidence (and in this field, the judge will have to rely on the knowledge of experts in the field), as being more than debatable.

“Thus, with so many scientific doubts, expressed by experts in the field, which are the ones that matter here, as to the reliability of such tests, ignoring the parameters of their performance and there being no diagnosis made by a doctor, in the sense of existence of infection and risk, it would never be possible for this court to determine that C ... had the SARS-CoV-2 virus, nor that A., B ... and D ... had high risk exposure,” concluded the judgement in relation to the case which has ultimately calls into question the reliability of the tests.

Meanwhile, the decision of the court has been damned by scientists in Portugal. According to a report in Públicio, the judges from the Lisbon Court of Appeal misread two scientific articles and the scientific consensus on PCR testing is “absolute”.

“The statement is false”, Vasco Barreto, a researcher at the Center for the Study of Chronic Diseases (Cedoc) of the Faculty of Medical Sciences of the Universidade Nova de Lisboa told Público, who added that he believed the judges acted “irresponsibly”.

“PCR tests have a specificity and sensitivity greater than 95%. That is, in the overwhelming majority of cases they detect the virus that causes covid-19 ”.

This is indicated in a scientific article that is cited in the judgment, but that has been read “completely wrong” by the magistrates, according to Germano de Sousa, former President of the Ordem dos Médicos and owner of a network of laboratories.

The other study cited in the judgement was Correlation Between 3790 Quantitative Polymerase Chain Reaction–Positives Samples and Positive Cell Cultures, Including 1941 Severe Acute Respiratory Syndrome Coronavirus 2 Isolates, whose results were published by Oxford Academic in late September.

PCR tests ("polymerase chain reaction") are the most widely used diagnostic method in most countries to detect the presence of SARS-CoV-2 precisely because they are the most accurate in identifying the virus. This is a technique that amplifies the virus's genetic material in successive cycles - with each cycle the material doubles. In the study cited, the relationship between the ability of the samples collected to infect cells and the number of cycles required to obtain a “positive” result was tested.

“The proportion of samples that were no longer able to infect cells maintained in culture in the laboratory increased with the increase in the number of cycles required to obtain a positive signal. This is because after our body controls the infection there are fragments of the virus's genetic material that persist and decrease over days, when the individual no longer poses a danger to others, ”explains Vasco Barreto. Conclusions like these have helped health authorities in different countries to reduce mandatory quarantine periods for those infected and to dispense with a negative test to “discharge” a patient.

Now, from reading the article, the judges conclude that “the probability of a person receiving a false positive is 97% or higher”. According to the investigation, this only happens if the cycle threshold is higher than 35 "as it happens in most laboratories in the USA and Europe", reads the judgment. This information is considered to be inaccurate by Vasco Barreto, who states that where he works at Cedoc “42% of the positive tests, only 25 or less cycles were needed and there is scientific evidence of the high capacity of the virus to spread from “positive” cases to less than 25 cycles”.
 
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