Amid the misery of a pandemic that has claimed at least four million lives, the scientific search for its origins has itself become toxic.
While it is now hideously ubiquitous, Sars-Cov-2 is still only an 18-month-old disease. And the search for its start was officially set in motion in 2020 by a World Health Organization investigative team. pg slot
Questions over its conclusions have escalated into a heavily politicised feud. Some research scientists, who have tried to unpick the pandemic's origins, have been accused of conspiracy and cover-up - based on no evidence.
Now, 21 researchers - all seeking to understand how a virus that originated in bats transferred into humans - aim to "set the record straight" by publishing their summary of the scientific evidence about the pandemic's beginning.
"It's not true that we don't know where it came from - we just don't know how it got into humans," says Glasgow University virologist Prof David Robertson.
It is widely accepted that an ancestor of the virus was originally a disease circulating harmlessly in wild bats. But it is vital to discover how, where and exactly when that first made its way into a person to prevent a similar future outbreak.
There is no definitive piece of evidence - no Covid-positive bat or a confirmed first human case - to show conclusively how it started. That may never be known, but the scientists who wrote this latest report want to clarify the available evidence and what it means.