GrumpyRabbit on Nostr: _An rtPCR cycle count above 24 almost always detects only viral dust and/or old ...
_An rtPCR cycle count above 24 almost always detects only viral dust and/or old coronavirus (not necessarily SARS-Cov-2)_
FTA: The overall examination of the evidence suggests that RT-PCR results in the context of using Ct values, do in fact yield a valuable surrogate or proxy for infectious virus detection which is key to decision-making on infection control and quarantine steps. The predominant finding is that a Ct value of up to 40 is currently used globally to guide a designation of ‘positive’ status. The CDC uses this cut point of 40 cycles to aid in denoting positivity.5 We however think that this is too sensitive and remains at risk of detecting non-viable SARS-CoV-2 based on the examined evidence. When less than the reported thresholds in Table 1 column A, infectivity (contagiousness) is high and outcomes are worse and above the Ct thresholds in column B, infectivity is very low (if at all existent once above a Ct value of ~30) and viral load is very low. As observed in Table 1 and the provided evidence, it appears that a Ct value threshold of between ~25 to 30 is more reflective of high SARS-CoV-2 viral load and as discussed in the literature, a likely indication of greater infectivity. On balance, a Ct value of 25 (as a surrogate for viral load) appears optimal when all of the reported evidence is considered, and beyond a Ct value of 30, we propose that infectivity drops off dramatically, as per the reported evidence. This is in line with the contention by Bullard et al.9 who stipulated that COVID-19 patients with a Ct value > 25 are not infectious given the virus cannot be detected in culture beyond a Ct of 25. We also propose at least 10 days eviction that is in line with what has been reported by Jaafar et al.13 Note, Rhee et al.14 reported no virus being isolated from samples after day 8.
https://palexander.substack.com/p/i-wrote-this-paper-on-cycle-count
FTA: The overall examination of the evidence suggests that RT-PCR results in the context of using Ct values, do in fact yield a valuable surrogate or proxy for infectious virus detection which is key to decision-making on infection control and quarantine steps. The predominant finding is that a Ct value of up to 40 is currently used globally to guide a designation of ‘positive’ status. The CDC uses this cut point of 40 cycles to aid in denoting positivity.5 We however think that this is too sensitive and remains at risk of detecting non-viable SARS-CoV-2 based on the examined evidence. When less than the reported thresholds in Table 1 column A, infectivity (contagiousness) is high and outcomes are worse and above the Ct thresholds in column B, infectivity is very low (if at all existent once above a Ct value of ~30) and viral load is very low. As observed in Table 1 and the provided evidence, it appears that a Ct value threshold of between ~25 to 30 is more reflective of high SARS-CoV-2 viral load and as discussed in the literature, a likely indication of greater infectivity. On balance, a Ct value of 25 (as a surrogate for viral load) appears optimal when all of the reported evidence is considered, and beyond a Ct value of 30, we propose that infectivity drops off dramatically, as per the reported evidence. This is in line with the contention by Bullard et al.9 who stipulated that COVID-19 patients with a Ct value > 25 are not infectious given the virus cannot be detected in culture beyond a Ct of 25. We also propose at least 10 days eviction that is in line with what has been reported by Jaafar et al.13 Note, Rhee et al.14 reported no virus being isolated from samples after day 8.
https://palexander.substack.com/p/i-wrote-this-paper-on-cycle-count