Why are some Covid-19 patients positive for longer?

Covid-19 cases around the world have been detected since the beginning of the pandemic thanks to tests such as PCR. They detect whether or not a person is positive, but since the beginning of the global health emergency, there have been cases of people who have tested positive for Covid-19 for a long time after having been diagnosed with the disease, something that has now been analyzed in a study.Why are some Covid-19 patients positive longer than others? Doctors began to notice this rarity already during the first months of the pandemic: some patients who had contracted the infection continued to give results inexplicably positive even after several months.One of the first explanations that were considered for the fact of testing positive for weeks and even months, is that people were infected with Covid again, although it was finally discarded since the analyzes with these patients gave as results that despite remaining positive after a long time, they did not have live virus cells. It is now that the Institute’s laboratory Whitehead and Professor Rudolf Jaenisch have published an article that could finally explain why this happens. The answer would be that the genetic consequence of the RNA of the SARS-CoV-2 virus could be integrated into the genome of the host cell, a process called reverse transcription, which results in that some sections of the genome can be read in RNA and therefore detectable during swab testing. In fact, about 8% of our DNA is made up of the remains of ancient viruses, and some of them depend on integration into human DNA to replicate.These are called “retroviruses”, hence despite having overcome the disease and not having living SARS-CoV-2 cells, patients continue to test positive. “SARS-CoV-2 is not a retrovirus,” explains Liguo Zhang, first author of the study to be published, “which means that it does not need reverse transcription for its replication. However, non-retroviral RNA virus sequences have been detected in human genomes. ‘ Professor Rudolf Jaenisch and researcher Liguo Zhang hope to discover whether these integrated sections of DNA could be responsible for some long-term autoimmune consequences in people with COVID-19, but for the moment they are satisfied with having answered the initial question that was posed.