The study was cited in health warnings around the world and appeared to be a model of international collaboration in a moment of crisis. Within days, though, the researchers quietly withdrew the paper, which was replaced online by a message telling scientists not to cite it. A few observers took note of the peculiar move, but the whole episode quickly faded amid the frenzy of the coronavirus pandemic.
What is now clear is that the study was not removed because of faulty research. Instead, it was withdrawn at the direction of Chinese health officials amid a crackdown on science. That effort kicked up a cloud of dust around the dates of early Covid cases, like those reported in the study.
