What do we actually know about where COVID-19 came from?
Most scientists lean one way, some intelligence agencies the other, and as of the sources read in 2026 the question was still unresolved.
▶ Start the storyNobody has proved it either way. The origin of COVID-19 is not definitively known. Most scientists believe the virus spread to humans through natural zoonotic transmission from bats, as in the SARS-CoV-1 and MERS-CoV outbreaks, and a 2024 survey of 168 experts, mostly epidemiologists and virologists, found they viewed zoonosis as 77% likely and a lab leak as 21% likely on average. But a laboratory escape has not been definitively ruled out, and a minority of scientists favour it.
What 168 experts said (2024 survey, average)
% likelihood
| Average likelihood given by experts | |
|---|---|
| Zoonosis | 77 % likelihood |
| Lab leak | 21 % likelihood |
What supports the natural route? In July 2022 two papers in Science described epidemiological and genetic evidence suggesting the pandemic likely began at the Huanan Seafood Wholesale Market in Wuhan. A 2024 study of market samples found genetic material of possible intermediate hosts, most likely raccoon dogs. The earliest human cases were identified in Wuhan, but the index case remains unknown.
What keeps the other idea alive? The Wuhan Institute of Virology had researched SARS-like bat coronaviruses since 2005, and in 2021 the former CDC director Robert Redfield said that in his opinion a laboratory escape was the most likely cause. US intelligence agencies have been split, each stating its confidence. In an August 2021 assessment, four agencies favoured a natural origin with low confidence, three were undecided, and the FBI supported a lab leak with moderate confidence. In 2023 the Department of Energy shifted to a lab leak with low confidence, and in 2025 the CIA said a lab leak was "more likely", also with low confidence.
In 2025 the WHO's expert group SAGO said a zoonotic origin has the weight of available evidence, but that the question remains unresolved without more primary data, such as early patient records and laboratory biosafety records from Wuhan.
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Recap
As of 2026, most scientists lean towards natural spillover, a lab escape is not ruled out, and the decisive primary data is still missing.
💡 A trick to remember it · Two doors, no key yet: one door is wider, but nobody has found the key that closes the other.
Surprising fact · As of 2025 the WHO's SAGO said the question remained unresolved without early patient records and laboratory biosafety records.
Sources (2)
No source, no claim. Every fact in this lesson (16 claims) cites at least one of these.