Since the early days of the pandemic, researchers have known that people with COVID-19 can spread the disease before they develop symptoms and even …
Since the early days of the pandemic, researchers have known that people with COVID-19 can spread the disease before they develop symptoms and even if they never feel sick. A study published in the Journal of the American Medical Association on Thursday quantifies just how many new cases are transmitted from people without symptoms: at least 50%. The findings echo estimates that the Centers for Disease Control and Prevention provided in November, when the agency said people without symptoms were “estimated to account for more than 50% of transmissions.” Jay Butler, deputy director for infectious diseases at the CDC and a lead author of the new study, said the findings reinforce the importance of following public-health guidelines about mask wearing and distancing. “There was still some controversy over the value to community mitigation — face masks, social distancing, and hand hygiene — to limit spread,” Butler told Business Insider. “This study demonstrates that while symptom screening may have some value, mitigation, as well as strategically planned testing of persons in some setting, will be a significant benefit.
