South Korean K-pop superstars BTS appeared in an empty hall to live-stream a press conference promoting their new album amid widespread concern about the spread of the deadly coronavirus. South Korea has seen a spike in Covid-19, the illness caused by the virus, and has called for the public to avoid mass gatherings. As of February 25, 2020, South Korea had confirmed 833 infections and 8 deaths from the coronavirus. More than half of the nation’s cases have been found in the southern city of…