China CDC Weekly · 20 authors, 14 centres
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This narrative review outlines the scientific framework for tracing SARS-CoV-2 origins, including evidence-chain requirements and hypotheses. It reports that environmental surveillance of 1,380 samples from the Huanan Seafood Market found 73 SARS-CoV-2-positive samples with no virus detected in 18 animal species, indicating the market likely acted as an early amplifier rather than confirming an animal-to-human origin.
This narrative review discusses the systematic approach to tracing SARS-CoV-2 origins, distinguishing between global zoonotic origin and localized introduction routes. The authors describe evidence-chain requirements—epidemiological, laboratory, and molecular—needed to establish a transmission link between a putative source and an index case. A central focus is the Huanan Seafood Market (HSM) surveillance effort: 1,380 environmental and animal samples collected from January to March 2020 were tested by RT-qPCR, yielding 73 positive environmental samples and three live virus isolates sharing 99.980% to 100% nucleotide identity with early human case isolates. No virus was detected in animal swabs covering 18 species. DNA barcoding of environmental samples showed high Homo sapiens abundance, suggesting human-derived contamination. Limitations include the inability to rule out human or cold-chain introduction and the impossibility of confirming animal-to-human transmission from available data. The review concludes that origin tracing remains an ongoing, evidence-driven scientific endeavor.
