Why we still don’t know where COVID-19 came from. And why we need to find out.

Five years after COVID-19 emerged, killing millions, costing trillions, and disrupting global life, we still don’t have a definitive answer as to the origins of the pandemic and the virus. This continued uncertainty is not due to scientific limitations but the withholding of critical information, particularly by China.

In June 2025, the WHO’s Scientific Advisory Group for the Origins of Novel Pathogens (SAGO), a panel of 27 international experts, published its most thorough analysis to date. What SAGO said is clear: Without China providing fundamental data, definitive conclusions remain impossible.

SAGO explicitly called for detailed records from several countries, especially China, but also Germany and the United States. While we can reasonably assume that the United States and Germany withheld portions of the requested intelligence to protect sources, methods, or collection practices, China withheld information that in most countries is treated as publicly available health information, such as early viral genome sequences, laboratory safety documentation, and detailed environmental samples from animal markets. We recognize that some of these data may be politically sensitive, as it relates to wildlife trade regulations or national biosecurity programs. Nonetheless, during a pandemic, China’s obligations under the International Health Regulations must take precedence.

As stated in the legally binding International Health Regulations (2005), each country must “notify WHO … within 24 hours” of assessing a potential public health emergency of international concern (Article 6) and must also respond to WHO requests to “verify” outbreaks, even when identified through unofficial sources (Article 9). China’s governmental response—issued on April 25, 2025 in its official white paper, “COVID-19 Prevention, Control and Origins Tracing: China’s Actions and Stance”—declared the investigation “finished.” Rather than suggesting that SARS-CoV-2 emerged from bats or susceptible animals, China insists, instead, that the virus was imported on frozen food.

This far-fetched “cold-chain hypothesis”, which posits that SARS-CoV-2 was introduced into animal markets in China via imported frozen products, is not supported by scientific evidence. SAGO has clearly stated that no evidence suggests transmission of the virus to humans from frozen products at the Huanan Seafood Market, or any other market in Wuhan, in the critical late-2019 period. The very small number of positive samples detected in mid-2020 are more plausibly explained by contamination by infected individuals within China, during a period when the virus was already endemic. Thus, to many observers, the frozen food claim appears more like a strategic effort to deflect responsibility rather than a scientifically sound explanation.

The issue extends beyond China’s narrative to include the perception around the world that its response involved systematic obstruction of data access. Early viral genome sequences remain unreleased, and environmental data from Wuhan’s Huanan Seafood Market were shared only after international researchers briefly gained access online. Crucially, China continues withholding information on wildlife supply chains and laboratory audits, particularly records from the Wuhan Institute of Virology and Wuhan CDC, hindering the ability to clarify the likelihood of a lab-related origin for the pandemic. Even basic scientific records, such as virus sample inventories, lab experiment logs, staff health records, and documentation of animal virus research, remain inaccessible. These kinds of data are not exotic or sensitive; they are the bread and butter of outbreak investigations, and their absence prevents even a disciplined inquiry into the possibility of a laboratory role.

SAGO’s statement that “there is no corroborating evidence” for a lab-leak hypothesis is often misunderstood by the public as exoneration for the virus laboratories in Wuhan, yet it is a scientific expression of skepticism due to an imposed absence of data, not active disproval.

China’s lack of transparency is particularly troubling given its unmatched scientific capabilities. Chinese institutions now lead globally in pathogen discovery and surveillance. They routinely collect and analyze samples across continents, including from insects and wildlife in Africa and elsewhere, with a level of resolution and scale that exceeds most Western efforts. For example, Chinese studies often include detailed sequencing efforts on individual mosquitoes, while comparable studies elsewhere rely on pooled mosquito samples or more limited data.

Yet when it comes to the origins of SARS-CoV-2, an outbreak that began in their own country, this scientific capability, so evident elsewhere, has conspicuously vanished from view. This differs markedly from China’s response to the original SARS outbreak in 2003–2004, when their researchers contributed openly to tracing the virus’s origin. Chinese officials frequently emphasize that their COVID-19 response was shaped by lessons from that first SARS crisis. But on the most critical scientific question, where the virus came from, those lessons were not applied. Beyond legal duties, scientists and public health institutions bear a deep moral responsibility to act transparently in the service of the public. Had such an outbreak emerged in New York or Berlin, researchers like ourselves would have been expected to open their lab notebooks and data to the world without hesitation—which we would have done. That is not just procedure—it is principle.

Many international experts increasingly view this pattern of behavior as a deliberate strategy of denial and deception, rather than isolated mistakes or confusion. Indeed, evidence of obfuscation is extensive, including initial denials of human-to-human transmission, the silencing of early whistleblowers like Dr. Li Wenliang, and the severe underreporting of cases and deaths.

Why does this still matter, five years later? The point isn’t blame; it’s prevention. Identifying the pandemic’s origin and route of transmission, including any potential animal sources, directly informs surveillance priorities, containment strategies, and biosecurity reforms critical to preventing future pandemics.

There will be a next biological event. Humanity is more numerous, more densely packed, and more interconnected than at any point in history. As population density increases, so too does the speed and scale at which infectious agents can spread. The number and frequency of contacts between viruses and potential hosts, human and animal, are rising rapidly. Whether a future outbreak stems from a natural spillover or a lab-related incident, the outcome will be the same unless we act: more transmission, more disruption, more loss. Our task is not merely to respond to outbreaks but to reduce the likelihood that such events happen again.

Thus, we need to know how they start.

More broadly, China’s continued obstruction sets a dangerous precedent; it weakens international cooperation and undermines trust in the scientific process when both are most needed. No country—whether China, the United States, or others—should be exempt from scrutiny in a global health crisis of this scale. Transparency during crises of this magnitude is non-negotiable. Without it, future responses will inevitably falter.

We are at a critical juncture. This is no longer just a question of origins—it is a test of whether we, as a global community, are capable of confronting hard problems together. Do we value truth and preparedness enough to insist on clarity, even when politically uncomfortable? The answer will shape how we meet the next pandemic threat.

WHO member states must demand that China grant full access to withheld data and facilities. Accountability in public health must become the standard. This is not about Cold War-style accusations. With each passing year, it becomes harder to dismiss the sense that key facts about COVID-19’s origins are being deliberately withheld. As transparency erodes, mistrust grows, and the world becomes even more vulnerable to the next biological crisis.