A new pre-print study released online recently has provided strong evidence to support the "natural spillover" hypothesis on COVID-19, with results that are hard to reconcile with the "lab leak" hypothesis.
SARS-CoV-2, the virus that causes COVID-19, could have spilled from animals to people multiple times, according to the preliminary analysis of viral genomes sampled from people infected early in the pandemic.
The latest analysis, posted on the virological.org discussion forum, is based on a detailed examination of the genetic sequences of two early lineages, known as A and B, which have key genetic differences, obtained from people infected in late 2019 and early 2020.
"It is a very significant study ... If you can show that A and B are two separate lineages and there were two spillovers, it all but eliminates the idea that it came from a lab," a Nature news article quoted Robert Garry, a virologist at Tulane University in New Orleans, Louisiana, as saying.
If confirmed by further analyses, the findings would make the "lab leak" hypothesis less likely, researchers have said.