Editor’s note: On June 4, 2020, three of the authors on a May 22 Lancet paper cited in this story retracted their paper. The study found that taking hydroxychloroquine or chloroquine for COVID-19 raised the risk of death. Reports that the study might be based on faulty data provided by a company founded by coauthor Sapan Desai prompted the editors of the Lancet to issue an expression of...

Coronaviruses, one of a variety of viruses that cause colds, have been making people cough and sneeze seemingly forever. But occasionally, a new version infects people and causes serious illness and deaths. That is happening now with the coronavirus that has killed at least 26 people and sickened at least 900 since it emerged in central China in December. The World Health Organization is...