Presymptomatic individuals accounted for 75 percent of confirmed COVID-19 transmission events --New study ,

Analysis of Asymptomatic and Presymptomatic Transmission in SARS-CoV-2 Outbreak, Germany, 2020

Catching the coronavirus from people who are asymptomatic, individuals who are infected but never have symptoms, may be exceptionally rare, according to a small but thorough study of 59 people who had the virus and 254 people they interacted with. However, presymptomatic individuals, those who are infected but haven’t yet begun to show symptoms, accounted for 75 percent of confirmed transmission events, researchers report in an April dispatch of Emerging Infectious Disease.

The seven asymptomatic cases did not transmit the virus to any of their contacts. Twenty-two of the 29 transmission events occurred when an infected person who was not yet showing symptoms interacted with people outside of their household. The study underlines the importance of isolation after testing positive, to reduce the chance of transmission even before symptoms start. ...