Evolving Epidemiology and Impact of Non-pharmaceutical Interventions on the Outbreak of Coronavirus Disease 2019 in Wuhan, China

Chaolong Wang; Li Liu; Xingjie Hao; Huan Guo; Qi Wang; Jiao Huang; Na He; Hongjie Yu; Xihong Lin; An Pan; Sheng Wei; Tangchun Wu

The outbreak started from the urban districts and gradually spread to the suburban and rural areas across the four periods, leading to strong geographic differences with the highest attack rates in the urban districts (Fig. S2) . The average daily attack rate per 10 6 people dramatically increased from 2.2 (95% CI, 2.0 to 2.4) before January 11, to 44.9 (43.6 to 46.2) between January 11 and 22, and to 150.9 (148.3 to 153.5) between January 23 and February 1, while dropped to 54.1 (52.9 to 55.3) after February 2 (Fig. 3A) . Similar patterns were observed for men and women, with slightly higher attack rate in women (Fig. 3A) . A total of 1316 healthcare workers were infected, representing 5.1% of the total cases ( Table 1) The median age of the patients was 57 years, with the majority (n=19，693, 75.9%) aged 40 to 79 years ( Table 1) . The attack rate peaked in the third period then declined in the fourth period for those older than 20 years, while it continued to increase throughout the periods for children (age <20 years) (Fig. 3B) , particularly for the infants below 1 year old (Fig. 3C) .