On the Controversies Surrounding the Lab-Leak Theory of COVID-19

In April 2025, the White House of the United States officially declared on its website that COVID-19 originated from a laboratory in Wuhan, China.1 This announcement has sparked significant controversy, as it may be seen as a case where political considerations have influenced, or at least appeared to influence, the interpretation of scientific matters.

The origin of COVID-19 remains a topic of vigorous scientific debate. The most widely supported theory is the natural spillover hypothesis, which posits that the virus was transmitted to humans through a process of accumulated mutations while circulating among animals. This theory is backed by numerous genomic analyses and evolutionary biology studies that support the natural emergence of SARS-CoV-2,2,3,4,5 with concrete evidence showing adaptation processes through recombination events among various hosts such as bats and pangolins.

The second hypothesis is the so-called “lab-leak theory,” suggesting that a new variant may have accidentally escaped from the Wuhan Institute of Virology (WIV) during serial passage or gain-of-function research on SARS-related viruses. Some circumstantial evidence seems to support this theory, such as reports that some WIV researchers showed COVID-like symptoms early on, records of high-risk coronavirus experiments led by Dr. Shi Zhengli’s team, and the fact that the earliest outbreak occurred in Wuhan.6 However, the viruses used in these experiments were not physically present but rather consisted of synthesized genetic sequences, meaning they were not complete, nor infectious viral particles capable of replication, and the pseudo-virus experiments conducted to test human cell entry lacked the ability to replicate. Dr. Shi Zhengli consistently emphasized from the outset that the virus was unrelated to their laboratory work.7

The third hypothesis is that the virus was deliberately engineered by the Chinese government or military as a biological weapon. This theory, however, lacks scientific credibility for multiple reasons. Most notably, if the virus were indeed developed as a bioweapon, there should have been a pre-developed vaccine or antidote to protect the developer's own population, which is a fundamental principle in biological warfare.8,9 In reality, China suffered massive losses during the COVID-19 pandemic. It is implausible to assume that any government would orchestrate such a self-destructive act.

That said, the emergence of the second and third theories cannot be dismissed solely as conspiracy thinking. Given the Chinese government's early actions—such as suppressing information, delaying disclosure of critical data, and silencing Chinese medical professionals—skepticism toward its transparency and credibility is not entirely unfounded. This lack of transparency severely hindered an objective investigation into the origin of the virus and fueled the spread of the lab-leak or intentional manipulation hypotheses. While the first theory has greater scientific support, if critical facts were indeed concealed by the Chinese authorities, even the best-supported theory might eventually collapse. However, such skepticism must be carefully distinguished from unsubstantiated claims in order to preserve the integrity of scientific reasoning.

The key principle is that support for any hypothesis must be reserved until it is backed by sufficient scientific evidence. The White House’s recent statement deviates sharply from this principle. For a national government to officially declare a politically convenient theory while scientific uncertainty persists undermines both academic freedom and the pursuit of truth.

This is not merely an issue of the United States. When science is reduced to a political tool, the consequences can reverberate across the global scientific community and among infectious disease experts. Such official pronouncements risk fostering public distrust and even targeting researchers who are engaged in fact-based inquiry into the origins of the virus. What is most needed now is not conclusion, but sustained questioning and rigorous analysis grounded in evidence.

In times like these, we must resolutely uphold the value of science and muster the courage to resist anti-scientific pressure.

To conclude, here are four guiding principles for infectious disease specialists in the face of upcoming challenges:

1. Do not be swayed by unverified information; base scientific discussions on peer-reviewed evidence.

2. Acknowledge uncertainty in origin theories but remain cautious of interpretations driven by ideology or political agenda.

3. Foster mutual respect within the scientific community and promote open discussion of competing hypotheses.

4. Communicate with the public responsibly, offering balanced and evidence-based explanations as professionals.

Science begins with questions and derives its answers through evidence. When political interference enters this journey—as illustrated by the White House’s premature endorsement of the lab-leak theory—the first victim is truth, and the second is ourselves.