A study of nearly 2,000 US Marine Corps recruits who underwent a strict phased quarantine before starting basic training identified several cases of asymptomatic COVID-19 spread, suggesting the need for the development of safer methods for similar settings involving young adults, including schools, sports, and camps, amid the pandemic.In the study, published yesterday in the New England Journal of Medicine, researchers at the Icahn School of Medicine at Mount Sinai Hospital and the Naval Medical Research Center studied 1,848 study volunteers during a supervised quarantine at a closed South Carolina college campus after they had quarantined at home for 2 weeks.