It's time the 'lab leak' theory is formally investigated
A year and a half into the pandemic, we still do not know exactly where the SARS-CoV-2 virus, which causes COVID-19, came from.
The prevailing view so far has been that the virus “spilled over” from bats into humans. But there are increasing calls to investigate the possibility that it emerged from a lab in Wuhan, China, where Covid first appeared at the end of 2019.
So what do we know for sure, and what do we need still to find out?