3 ms·
The trouble is, the moment the bar is lowered, the press will run scary articles about how the tests miss large numbers of people that are detected by the PCR t
by makomk 6y ago
The trouble is, the moment the bar is lowered, the press will run scary articles about how the tests miss large numbers of people that are detected by the PCR test and how there's no evidence that lower CT value equivalents correspond to lower infectivity. This has already basically happened in the UK after the government launched a trial of mass testing an entire city using one of the better and less cheap rapid tests. It undermines confidence in Covid testing as a whole.
- sradman 6y agoCorrelation Between 3790 Quantitative Polymerase Chain Reaction–Positives Samples and Positive Cell Cultures, Including 1941 Severe Acute Respiratory Syndrome Coronavirus 2 Isolates [1] paper from Clinical Infectious Diseases: > It can be observed that at Ct = 25, up to 70% of patients remain positive in culture and that at Ct = 30 this value drops to 20%. At Ct = 35, the value we used to report a positive result for PCR, <3% of cultures are positive. We need the right tool for the job. A positive daily lick-a-stick screening test should be confirmed with serum IgM and/or PCR testing. Each tool in our toolbox has a sweet spot and tradeoffs. The key to the daily screening test is that there is only a short window early in the infection that has a CT > 25. [1] https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1491/5912603 https://academic.oup.com/cid/advance-article/doi/10.1093/cid...
- bhickey 6y ago> lower CT value equivalents correspond to lower infectivity. Ct stands for cycle threshold: how many cycles did you need to run the PCR machine before crossing your detection threshold.