Remember PCR Tests?

Ed Fenton and his SubStack put out an excellent analysis of the PCR analysis and the controversy surrounding them. Here are some key highlights from the post:

1. Cycle Threshold (Ct) Issues

PCR tests work by amplifying viral RNA in cycles. The cycle threshold (Ct) is the number of times the genetic material is amplified to reach a detectable level.

• High Ct values can lead to false positives: If too many cycles (e.g., 35-45) are used, even tiny, non-infectious virus fragments can be detected, leading to a positive result even when a person is not contagious.

• Low Ct values can lead to false negatives: If too few cycles are run (e.g., under 25), an infection could be missed.

• Ct values were often not standardized: Different labs and countries used varying Ct thresholds, making it difficult to compare results.

2. Detecting Non-Infectious or Dead Virus

PCR tests can detect viral RNA long after an infection has resolved.

• Someone who recovered from COVID-19 weeks ago but still has trace viral fragments could test positive.

• PCR tests do not distinguish between live, infectious virus and inactive viral debris.

• This led to prolonged isolation for people who were no longer contagious.

3. Misinterpretation of Case Numbers

PCR test results were often used to determine “case numbers,” but:

• A positive PCR test does not necessarily mean an active case of COVID-19.

• Mass testing of asymptomatic individuals using PCR resulted in increased case counts, even when many of those cases were not infectious.

• This may have influenced policy decisions (lockdowns, restrictions) based on inflated or misunderstood data.

4. No Quantification of Viral Load

PCR tests can tell whether viral RNA is present, but they do not measure the actual amount of virus in the body.

• Someone with a very low viral load (and possibly non-infectious) could test the same as someone with a high viral load (and highly contagious).

• Without viral load data, public health policies (such as quarantining or contact tracing) may have been based on misleading or incomplete information.

5. Risk of Contamination and False Positives

PCR tests are extremely sensitive, meaning they can pick up even tiny amounts of genetic material.

• Lab contamination or improper sample handling can lead to false positives.

• Some mass testing campaigns had issues with false positives, potentially inflating case numbers.

• There were reports of contaminated test kits, leading to unreliable results.

6. Over-Reliance on PCR for Diagnosing COVID-19

Early in the pandemic, PCR tests were used as the gold standard, but:

• They were sometimes used without clinical symptoms, leading to misdiagnosis.

• Other diagnostic methods, like antigen tests or clinical assessments, were often dismissed.

• Relying solely on PCR results meant some people were labeled “infected” or “recovered” without considering their actual health status.

7. Potential Conflicts of Interest in Testing

• Many companies and institutions had financial incentives to promote widespread PCR testing.

• The more tests conducted, the more revenue for testing companies.

• Some governments and organizations pushed mass testing policies without considering the limitations of PCR.

Conclusion

PCR tests are a powerful tool, but they were often misapplied, misinterpreted, or over-relied upon during the COVID-19 pandemic. Issues with cycle thresholds, non-infectious detections, case count inflation, and contamination all contributed to concerns about their misuse. A more nuanced approach—considering viral load, symptoms, and alternative testing methods—might have led to more accurate public health responses.