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A correct positive PCR doesn't even guarantee infection - it just tells you that you have been infected within the last month or so. Old, inactivated viral RNA
by comicjk 6y ago
A correct positive PCR doesn't even guarantee infection - it just tells you that you have been infected within the last month or so. Old, inactivated viral RNA can still trigger a positive weeks later.
- refurb 6y agoIndeed, people testing positive months after all symptoms have disappeared don't appear to be infectious, the PCR is just picking up fragments of viral RNA. That said, I always understood RNA as being pretty fragile, so I'm surprised, but I do know that the fragility is heavily dependent up on structure - you can have RNA sequences that are pretty stable due to the tertiary structure (folding) that occurs.
- ejstronge 6y agoAre there examples of studies on people testing positive months later? qPCR is used in many settings for medical testing and the guidelines for other diseases are that residual bacterial RNA is cleared 7-14 days after successful antibiotic treatment. Obviously, COVID is caused by a virus, but a much longer period to clear viral RNA is not intuitive.
- _Gyan_ 6y ago> Are there examples of studies on people testing positive months later? Yes. However, it appears to not be live virus. https://www.medrxiv.org/content/10.1101/2020.07.21.20125138v1 https://www.medrxiv.org/content/10.1101/2020.07.21.20125138v...