Doping Regulator Knew of Previous Positive Tests by Chinese Swimmers

China’s Wang Shun, center, competing in the world swimming championships in Budapest in 2022. Chinese officials said he was among three top swimmers who tested positive on multiple occasions.After the revelation in April that 23 elite Chinese swimmers had tested positive for a banned substance months before the last Summer Olympic Games, China and the global antidoping authority vigorously defended their decisions to allow them to compete in the Games in 2021. The swimmers, they insisted, had not been doping.

But as they made those claims, China and the antidoping authority were both aware that three of those 23 swimmers had tested positive several years earlier for a different…