Asymptomatic people are responsible for the transmission of more than 50% of the coronavirus cases, a model from Centers for Disease Control and Prevention scientists shows.
Their findings reinforce the importance of following the agency’s guidelines: Regardless of whether you feel ill, wear a mask, wash your hands, stay socially distant and get a coronavirus test. That advice has been a constant refrain in a pandemic responsible for more than 350,000 deaths in the United States.
Fifty-nine percent of all transmission came from people without symptoms, under the model’s baseline scenario. That includes 35 percent of new cases from people who infect others before they show symptoms and 24 percent that come from people who never develop symptoms at all.
“The bottom line is controlling the covid-19 pandemic really is going to require controlling the silent pandemic of transmission from persons without symptoms,” said Jay C. Butler, the CDC deputy director for infectious diseases and a co-author of the study. “The community mitigation tools that we have need to be utilized broadly to be able to slow the spread of SARS-CoV-2 from all infected persons, at least until we have those vaccines widely available.”