Four in ten people infected with COVID-19 show no symptoms — but are still potential spreaders of the disease, according to a new study. The findings, published last week in JAMA Network Open, found that 40.5 percent of people diagnosed with COVID-19 globally were asymptomatic. However, researchers said this highlights the “potential transmission” of the virus unknowingly, particularly in certain settings. “Screening for asymptomatic infection is required, especially for countries and region that have successfully controlled SARS-CoV-2,” researchers from Peking University said. “Asymptomatic infections should be under management similar to that for confirmed infections, including isolating and contact tracing.”