A groundbreaking international investigation has presented strong evidence that the coronavirus responsible for the Covid-19 pandemic did not originate in Wuhan, China, disputing the lab leak theory promoted by former US President Donald Trump.

Published on May 7 in the peer-reviewed journal Cell, the research was led by the University of Edinburgh and included scientists from 20 institutions across the US, Europe, and Asia, including China. The team analyzed 167 bat coronavirus genomes, tracing the source of the virus to bat populations in northern Laos and southwest China’s Yunnan province, where its closest ancestor existed five to seven years before the pandemic began.

This discovery counters claims by the White House, which recently updated its website asserting a Chinese lab leak as the “real source” of Covid-19, highlighting headings such as “LAB LEAK” and “ORIGIN” in bold letters.

Researchers focused on sarbecoviruses, a group of coronaviruses that cause severe respiratory illnesses including SARS-CoV-1 from the 2002-2004 outbreak, and SARS-CoV-2, which triggered Covid-19. Lead author Jonathan Pekar noted that SARS-CoV-1 circulated in western China just before the 2002 outbreak, while SARS-CoV-2 emerged in western China or northern Laos years before appearing in Wuhan.

Genetic analysis showed the progenitor of SARS-CoV-2 evolved roughly 3,000 kilometers away from Wuhan—far beyond bats’ natural flight range—implying human activity likely spread the virus. Bats, which carry the virus without harm, are believed to have transmitted it to humans through zoonotic spillover.

The study reconstructed the viruses’ evolutionary paths across Asia, suggesting these coronaviruses have been present in bats of western China and Southeast Asia for thousands of years. Due to frequent genetic mixing (RNA recombination) in bats, pinpointing the exact lineage is challenging, so researchers broke down the virus genome into parts to identify the most recent common ancestor (MRCA).

The MRCA for SARS dates to around 2001, while that for SARS-CoV-2 is estimated around 2017. SARS-CoV-1 likely originated in Chinese provinces Sichuan, Guizhou, and Yunnan, whereas SARS-CoV-2’s ancestor might have developed in northern Laos.

The study supports the idea that wildlife trade networks, not natural animal migration, facilitated virus transmission to cities. Similar to past zoonotic outbreaks like the Manchurian plague of 1910, where railways helped spread infected animals, human transport likely played a key role.

China’s National Health Commission has suggested Covid-19 may have appeared earlier in the US, advocating for further investigations there. Meanwhile, Wuhan’s former Huanan Seafood Market, once thought to be the pandemic’s starting point, has been replaced by an eyeglasses market.