Twitter users and some media outlets begin to circulate allegations of a lab leak, which are widely repeated by the end of the month by Senator Tom Cotton (R-AR). Meanwhile, a group of Chinese researchers publish a Lancet article that complicates the initial “wet market” theory of the origin of COVID-19, seeding early scientific uncertainty about the birthplace of the new coronavirus.

Debate about the origins of COVID-19 within the scientific community begins to intensify when a molecular biochemist at the South China University of Technology publishes a paper theorizing that the virus must have escaped from a Wuhan laboratory. Later in the month, researchers at the Wuhan Institute of Virology (WIV) publish a Nature article claiming that COVID-19 is a bat-derived coronavirus.

Concerns about a lab leak go mainstream in the American media. A Washington Post article reveals that, in 2018, US State Department officials who visited WIV expressed concerns about inadequate safety precautions being taken in a lab studying bat coronaviruses. Both President Donald Trump and Secretary of State Mike Pompeo mention the lab leak hypothesis in public statements, and the US Office of the Director of National Intelligence reveals that it is working to figure out whether COVID-19 had zoonotic or experimental origins. In the meantime, Trump has the National Institutes of Health cancel their funding to the entity backing bat coronavirus research at WIV.