As a World Health Organization team digs into the origin of the Covid-19 pandemic, other scientists are unearthing tantalizing new clues suggesting that the virus behind it evolved naturally to infect humans.
At least four recent studies have identified coronaviruses closely related to the pandemic strain in bats and pangolins in Southeast Asia and Japan, a sign that these pathogens are more widespread than previously known and that there was ample opportunity for the virus to evolve.
Another new study suggests that a change in a single amino acid in a key component of the virus enabled or at least helped the virus become infectious in humans. Amino acids are organic compounds that form proteins.
Public-health officials say it is critical to identify the origin of the pandemic to take steps to avert future outbreaks, though it may take years to do so. These latest pieces of research add to evidence that the virus, called SARS-CoV-2, likely originated in bats and then evolved naturally to infect humans, possibly through an intermediary animal.
The studies also help explain why members of a WHO team that in February completed a four-week mission to Wuhan—the Chinese city where the first known cases of Covid-19 were found—advocate searching for the origin of the pandemic in other countries in addition to China, particularly those along its border in Southeast Asia.