Chinanews client April 2 (Peng Jingru) Wu Zunyou, chief expert of epidemiology, China Centers for Disease Control and Prevention said on April 2 that there was an article in the preprint of the Chinese Journal of Epidemiology two days ago This study was carried out by the Ningbo Centers for Disease Control and Prevention. They observed close contacts of confirmed patients and close contacts of asymptomatic infections and found that: 1. On average, each confirmed patient can spread nearly 3 patients, and the average Symptoms can spread to less than 1 patient. In other words, the transmission efficiency of asymptomatic infection is equivalent to about one third of the confirmed cases, which is at the individual level. 2. At the group level, the proportion of cases transmitted by asymptomatic infections to the total number of cases is only 4.4%, less than 5%, that is, at the group level, the spread of asymptomatic infections to the disease The contribution is relatively small.