Coronavirus may have circulated in humans for years

The SarsCoV2 virus may have circulated in humans for years before developing the genetic characteristics that led to the dramatic Covid-19 pandemic. To launch this new hypothesis is the international study that in the journal Nature Medicine has shown how the new coronavirus has a natural origin and was not born in the laboratory.

The research team (which includes US, British and Australian experts coordinated by the Californian center Scripps Research Institute) has examined the genetic characteristics of the virus, going so far as to exclude that it is the result of genetic manipulation.

Once established the natural origin, we are faced with two possible scenarios. The first hypothesizes that the virus evolved in animals, for example through the recombination of the coronaviruses of bats and pangolins, and then made the leap of species towards humans. This theory, supported by the link between the first cases of Covid-19 with the Wuhan fish market, has not yet found definitive evidence in animal studies: the few bat and pangolin coronaviruses analyzed so far, in fact, do not seem to be so similar to SarsCoV2 that can be defined as direct ancestors.

In light of these observations, a second scenario is outlined, which has so far remained in the background: the SarsCoV2 virus may have evolved after circulating undisturbed in humans for years. "It is possible that the ancestor of SarsCoV2 made the leap in humans, acquiring new genomic features as it went unnoticed from one person to another," the researchers write. "Once acquired, these adaptations would allow the pandemic to take off producing a sufficiently large number of cases."