By mid-January 2020, epidemiologists were doing just this for SARS-CoV-2 — but had not come to a consensus about their findings. Sam Scarpino, an epidemiologist who directs the Emergent Epidemics Lab at Northeastern University in Boston, Massachusetts, tweeted that the evidence didn’t confirm sustained human-to-human transmission. And he remembers Rivers responding to him in a direct message: “She said, ‘Dude, I think you’re wrong.’”