Silent transmission could be responsible for half of coronavirus cases in the US, according to a study published Monday in the Proceedings of the National Academy of Sciences.
The term "silent transmission" means the virus is transmitted through asymptomatic or pre-symptomatic patients, who are harder to find and trace.
How the study worked: The study, led by Alison Galvani of Yale University and colleagues, used coronavirus transmission models and existing research, which already indicated that asymptomatic infections account for 17.9% to 30.8% of all infections.
Based on these existing figures, the team found that presymptomatic people would account for 47% to 48% of transmission, and asymptomatic people would account for 3.4% to 6.6% of transmission.
What this means: The team found that even immediate isolation of all symptomatic cases would not be enough to get the spread under control. Authorities would need to identify and isolate more than one-third of silent transmitters, as well as all symptomatic cases, to prevent an outbreak.
Researchers emphasized the need for both testing and contact tracing to safely lift the current social distancing and stay-at-home restrictions.