Study finds early Wuhan COVID cases largely undetected
A modeling study looking at more than 32,000 confirmed coronavirus cases in Wuhan, China, offers fresh insights into features of the virus, including ease of transmission, effectiveness of nonpharmaceutical interventions such as social distancing and face masks, and the impact that undetected cases have on the spread of the disease. The analysis, published in the journal Nature, underscores the stealthy nature of the virus and adds to a growing body of research that suggests people infected with COVID-19 who went undetected or were asymptomatic, presymptomatic, or had only mild symptoms have been significant spreaders of the disease. Using statistical and epidemiological modeling to reconstruct the outbreak in Wuhan from Jan. 1 to March 8, researchers found that up to 87 percent of cases in the city during that time may have gone undetected and transmission rates during some of the earliest days could have been as high as 3.54 infections per single...