Chinese researchers isolated and mapped the virus that causes Covid-19 in late December 2019, at least two weeks before Beijing revealed details of the deadly virus to the world, congressional investigators said, raising questions anew about what China knew in the pandemic’s crucial early days.

Documents obtained from the U.S. Department of Health and Human Services by a House committee and reviewed by The Wall Street Journal show that a Chinese researcher in Beijing uploaded a nearly complete sequence of the virus’s structure to a U.S. government-run database on Dec. 28, 2019. Chinese officials at that time were still publicly describing the disease outbreak in Wuhan, China, as a viral pneumonia “of unknown cause” and had yet to close the Huanan Seafood Wholesale Market, site of one of the initial Covid-19 outbreaks. To read the full story.