Reply to thread

Message: <blockquote data-quote="briggart" data-source="post: 8101526" data-attributes="member: 6805135">The Spanish study came out a couple of weeks after a similar Italian study which found covid traces in wastewater in December 2019, but not in samples before that going back a couple of years. I asked to a biologist friend if it was possible that also in Italy covid was circulating back in spring 2019 and we missed it. He said that these tests look for specific portion of DNA from a virus, not the full DNA sequence. Given that DNA traces are small, they first need to artificially replicate any such DNA, and this process introduces some errors, so there is always the possibility that what was found comes from a related virus that is compatible with sars-cov-2 within the uncertainty given by these replication errors. Combined with the fact that similar studies show it took 1-2 months between traces of virus starting to appear in wastewater and large scale epidemic, he found unlikely that the virus stayed dormant in Spain for almost a year without either leaving traces in the environment or in the medical history of patients. But I don't have any background in biology, so any gross error in the above is likely me misunderstanding/misremembering what I was told.</blockquote>