Editor's Note: This story was updated on May 19 to clarify that viral RNA, not infectious virus, was detected in the story on COVID-19 virus shedding.Patients with COVID-19 outside of Wuhan, China, shed virus RNA for a median of 17 days, according to a retrospective cohort study published yesterday in the International Journal of Infectious Diseases.Also, a study in the same journal found that third-generation transmission of the COVID-19 epidemic likely began on Jan 17 to 20 in Wuhan, then spread to the rest of Hubei province from Jan 23 to 24, while the mixed first- and second-generation transmissions interacted to worsen the outbreak.Shedding virus RNA for as long as 6 weeksIn the first study, researchers studied the clinical factors,