Pangolins and COVID-19: What the Science Actually Found

In February 2020, as researchers raced to identify the source of a novel coronavirus devastating Wuhan, a pre-print paper from the South China Agricultural University made a claim that travelled around the world faster than the virus itself: pangolins might be the intermediate host of SARS-CoV-2. The claim triggered headlines, accelerated already-declining public sympathy for the trade in pangolin scales and meat, and lodged an enduring association between pangolins and the COVID-19 pandemic in popular consciousness. Three years of subsequent peer review produced a far more complicated picture — one that neither vindicates nor entirely exonerates pangolins, but which is significantly more uncertain than early reporting suggested.

The Intermediate Host Hypothesis: How It Works

Zoonotic diseases — those that jump from animals to humans — typically follow one of two pathways. In direct spillover, a virus moves straight from a reservoir species (usually a bat or rodent) to a human. In indirect spillover, the virus replicates in an intermediate host that bridges the ecological or behavioural gap between reservoir and human. The intermediate host matters because it provides a population in which a virus can evolve, accumulate mutations that improve binding to human cell receptors, and reach sufficient concentrations to cause infection. SARS-1, the coronavirus responsible for the 2002-2004 epidemic, moved from horseshoe bats through civet cats to humans at wildlife markets in Guangdong, China. The assumption that SARS-CoV-2 followed a similar pathway was scientifically reasonable from the outset.

Pangolins became a candidate because of their presence at Chinese wildlife markets, their high-volume trafficking through the same ports where early COVID-19 cases clustered, and the biological logic that a stressed, immunocompromised animal in close contact with other stressed animals and human handlers represents an ideal spillover environment.

The Receptor-Binding Domain Finding

The specific scientific basis for the pangolin hypothesis came from genomic analysis of coronaviruses found in Malayan pangolins (Manis javanica) confiscated by Chinese customs authorities in 2017 and 2018. Two research groups, one at the South China Agricultural University and another led by Tommy Lam at the University of Hong Kong, independently identified betacoronaviruses in these pangolins. The viruses were designated Pangolin-CoV or pangolin-SARSr-CoV.

The finding that drew the most attention was the receptor-binding domain (RBD) of the pangolin coronavirus spike protein. The RBD is the molecular key that a coronavirus uses to enter cells: it binds to the ACE2 receptor on the surface of human respiratory cells. The RBD of the Malayan pangolin coronavirus shared 97 to 100 percent amino acid identity with the RBD of SARS-CoV-2 — an extraordinary degree of similarity in the functionally critical region of the virus.

This similarity carried a clear implication: if SARS-CoV-2 acquired its human-compatible RBD through recombination with a pangolin coronavirus, pangolins could have served as the environment in which a bat-origin virus evolved into a human pathogen. The hypothesis was scientifically plausible, mechanistically coherent, and backed by a specific quantitative finding. It was, for a time, the leading candidate explanation.

Why the Hypothesis Did Not Hold Up Under Scrutiny

Subsequent analysis substantially weakened the pangolin intermediate host hypothesis without fully eliminating it. The central problem was that the RBD similarity, while striking, was not accompanied by comparable similarity in the rest of the genome. Outside the receptor-binding domain, the pangolin coronavirus and SARS-CoV-2 differed enough to rule out a simple direct lineage. No single ancestor of SARS-CoV-2 has been identified in pangolins; the relationship, if one exists, appears to involve ancient recombination events rather than recent spillover.

A 2020 paper in Nature by Maciej Boni and colleagues, which constructed the most detailed phylogenetic analysis of SARS-CoV-2 ancestry published at that time, found that the closest known relative of SARS-CoV-2 was the bat coronavirus RaTG13, isolated from a horseshoe bat (Rhinolophus affinis) in Yunnan Province and sharing approximately 96.2 percent overall genome identity with SARS-CoV-2. This implied a common ancestor approximately 40 to 70 years prior. Pangolin coronaviruses were more distantly related in overall genome structure, suggesting they contributed to SARS-CoV-2 ancestry only through recombination — if at all.

A further complication arose from the sample quality of the original pangolin data. Several subsequent researchers noted that the pangolin coronavirus sequences were derived from animals that were sick and dying — animals whose tissues may have hosted viral mixtures or degraded samples susceptible to contamination. The reliability of the original genomic data was questioned without being definitively resolved.

Recombination: A Possible but Uncertain Role

The most defensible current scientific position is that pangolins may have contributed to the evolutionary ancestry of SARS-CoV-2 through ancient recombination, but are not confirmed as the proximate intermediate host through which the virus jumped to humans in 2019. Recombination between coronaviruses is common; a bat virus that infected pangolins, or vice versa, could have produced hybrid progeny that combined elements of both genomes. The RBD similarity between pangolin coronaviruses and SARS-CoV-2 is consistent with such a recombination event occurring in the evolutionary past.

But recombination in the distant past is different from pangolins serving as the spillover bridge in Wuhan in late 2019. The absence of live pangolins from the Huanan Seafood Market — the cluster centre of early cases — weakens the market-based intermediate host scenario for pangolins specifically, though some pangolin products were present at adjacent markets. The WHO-convened team that visited Wuhan in 2021 rated animal-to-human spillover through an intermediate host as "likely to very likely," but did not identify pangolins as the specific intermediate host.

The Impact on Conservation: A Complicated Legacy

The pangolin-COVID association had measurable consequences for conservation. In the short term, it increased global awareness of the illegal pangolin trade and generated significant media coverage of a species that struggles to attract public attention. China temporarily removed pangolin scales from its official list of approved traditional medicine ingredients in June 2020, a decision partly attributed to COVID-related scrutiny of wildlife markets. The international pressure that followed accelerated regulatory changes that had been stalled for years.

The longer-term picture is more complicated. The association also triggered a backlash. In parts of China and Southeast Asia, some media framed the pangolin-COVID hypothesis as a Western attack on traditional practices, generating defensive reactions that made conservation advocacy harder. The simplification of the science — which was always ambiguous — into confident "pangolins caused COVID" headlines meant that when the hypothesis was qualified by subsequent research, it created an impression that conservation advocates had overstated the case. This was not helpful.

Conservationists working in southern Africa, including the African Pangolin Working Group, took a measured stance: they acknowledged the scientific finding, supported continued investigation, and avoided conflating a hypothesis about a Southeast Asian pangolin species (Manis javanica) with the African ground pangolins (Smutsia temminckii) they work with, which have not been found to carry related coronaviruses.

What Remains Unknown

As of 2026, the origin of SARS-CoV-2 remains one of the most consequential unresolved questions in modern science. The two principal hypotheses — natural zoonotic spillover and a laboratory-related incident at the Wuhan Institute of Virology — have not been conclusively distinguished by the available evidence. The WHO's Scientific Advisory Group for the Origins of Novel Pathogens (SAGO) has repeatedly called for unrestricted access to primary data from the early outbreak period. That access has not been fully provided.

What can be said with confidence: coronaviruses related to SARS-CoV-2 circulate in horseshoe bat populations across southern China and Southeast Asia. Pangolins carry coronaviruses that share functionally important similarities with SARS-CoV-2. The evolutionary history of SARS-CoV-2 almost certainly involved bat hosts, may have involved recombination events in other species, and produced a virus uniquely well-adapted to human ACE2 receptors by the time it caused the first documented human cases. Whether that adaptation occurred naturally through spillover chains, or artificially through laboratory manipulation, or through some combination of factors, remains genuinely uncertain.

Why It Matters for Pangolin Conservation

The COVID-19 pandemic demonstrated, more viscerally than any conservation report, the cost of wildlife trafficking networks. Wet markets in which live wild animals are stressed, immunocompromised, and mixed in conditions ideal for cross-species viral transmission represent a documented biosecurity risk. Whether or not a specific pangolin was involved in the origin of SARS-CoV-2, the trade in wildlife — including the trafficking of Malayan and Chinese pangolins through the same markets and networks implicated in early COVID research — represents a risk that extends beyond conservation into global public health.

That argument stands regardless of how the origin debate resolves. It is the strongest and most scientifically defensible contribution of the pangolin-COVID association to conservation discourse: not that pangolins caused COVID-19, but that the conditions that drive pangolin trafficking are also conditions that create pandemic risk. The two problems share roots, and addressing them requires overlapping solutions — reduced demand for illegal wildlife products, better market regulation, and expanded habitat protection that keeps wild animals out of human supply chains.