Slack Messages Released by Sen. Rand Paul Reveal Authors Privately Questioned COVID-19 Natural Origin

Internal Slack messages released by Sen. Rand Paul show the four authors of the March 2020 Nature Medicine paper 'The Proximal Origin of SARS‑CoV‑2' privately expressed uncertainty about a strictly natural origin of the virus. Their private comments appear to contrast with the paper's public conclusion that the virus showed no signs of laboratory manipulation.

What the messages reveal

The exchanges involve Kristian Andersen, Robert Garry, Eddie Holmes and Andrew Rambaut. In the messages, Andersen estimated roughly a 30% probability that SARS‑CoV‑2 had a laboratory origin, while Holmes initially estimated 20% and later revised that down to 10%. Andersen also wrote that the group lacked "hard evidence one way or the other" and said recent information reduced his confidence in the paper's definitive wording.

The P4 laboratory, center, on the campus of the Wuhan Institute of Virology in China. The lab has been at the center of alleged theories that COVID-19 was engineered in a lab.

Debate Over The Furin Cleavage Site

The conversations show sustained debate about the furin cleavage site, a genetic feature central to the lab‑leak discussion. Andersen referred to some potential "smoking(ish) guns" that made him "not comfortable" and diminished his confidence at that stage.

Coordination And Tensions

According to the released documents, the authors coordinated with U.S. intelligence officials and leaders at the National Institutes of Health while publicly defending their conclusions. The messages also document tensions with prominent coronavirus researcher Ralph Baric, including professional rivalry and suspicion that he may have tried to undermine the group.

Officials with U.S. Customs and Border Protection were allegedly prepared to question and search Peter Daszak, inset, upon his return to the U.S. from the World Health Organization's investigation into the origins of COVID-19, before the FBI intervened and asked agents to stand down, according to documents released Monday by Sen. Rand Paul, R-Ky.

Leaked Peer Review And Law‑Enforcement Notes

The team suspected an anonymous peer‑review leak—nicknamed 'Deep Throat' in their exchanges—and at one point considered Baric a possible source. The material also includes documents indicating that U.S. Customs and Border Protection agents prepared to question British zoologist Peter Daszak upon his return from the World Health Organization's origins probe, before the FBI intervened and asked agents to stand down.

Broader Context

The World Health Organization convened a scientific advisory group that released a report concluding the pandemic most likely began from a zoonotic spillover, either directly from bats or via an intermediate host. Separately, Sen. Rand Paul subpoenaed Dr. Anthony Fauci, who is scheduled to testify before the Senate Homeland Security and Governmental Affairs Committee about the origins of the virus; some critics have accused Fauci of misleading Congress, allegations he disputes.

Note: The released Slack messages document private assessments and debate among scientists at a particularly uncertain early stage of the pandemic. Private views and evolving judgments are common in scientific discussions and do not by themselves prove misconduct.