Origin of SARS-CoV-2
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Since the beginning of the COVID-19 pandemic, there have been efforts by scientists, governments, and others to determine the origin of the SARS-CoV-2 virus. Similar to other outbreaks, the virus was derived from a bat-borne virus and most likely was transmitted to humans via another animal in nature, or during live wildlife trade such as that in food markets. While other explanations, such as speculations that SARS-CoV-2 was accidentally released from a laboratory have been proposed, such explanations are not supported by evidence. Conspiracy theories about the virus's origin have proliferated widely.
Research is ongoing as to whether SARS-CoV-2 came directly from bats or indirectly through an intermediate host, such as pangolins, civets, or raccoon dogs. Genomic sequence evidence indicates the spillover event introducing SARS-CoV-2 to humans likely occurred in late 2019. As with the 2002–2004 SARS-CoV-1 outbreak, efforts to trace the origins of SARS-CoV-2 have spanned years, with the World Health Organization and independent researchers conducting investigations into the origins of SARS-CoV-2 since 2020, but as of 2025, no conclusive determination has been made regarding its specific geographic and taxonomic origins.
In 2025 the World Health Organization's Scientific Advisory Group for the Origins of Novel Pathogens, and an independent review, concluded that a zoonotic origin has the "weight of available evidence" and emphasized that the origin remains unresolved without additional primary data, including early patient records and sequences, detailed wildlife supply-chain documentation, and laboratory biosafety and health records from Wuhan institutions.
In 2026, virologist Joel Wertheim and colleagues at UCSD published a study in the journal Cell which compared evolutionary patterns of outbreaks of Ebola, influenza and other viruses. They found that the mutation pattern of SARS-CoV-2 matched five naturally occurring outbreaks, but did not resemble the 1977 Russian flu outbreak which was likely from a lab leak. Wertheim and other WHO-designated experts favored the origin of SARS-CoV-2 to have been in bats which passed it to animals sold in the Wuhan market.