Epidemic size of novel coronavirus-infected pneumonia in the Epicenter Wuhan: using data of five-countries' evacuation action

Background: Since late December 2019, novel coronavirus-infected pneumonia (NCP) emerged in Wuhan, Hubei province, China. Meanwhile, NCP rapidly spread from China to other countries, and several countries' government rush to evacuate their citizens from Wuhan. We analyzed the infection rate of the evacuees and extrapolated the results in Wuhan's NCP incidence estimation. Methods: We collected the total number and confirmed cases of 2019-nCov infection in the evacuation of Korea, Japan, Germany, Singapore, and France and estimated the infection rate of the 2019 novel coronavirus (2019-nCov) among people who were evacuated from Wuhan with a meta-analysis. NCP incidence of Wuhan was indirectly estimated based on data of evacuation. Results: From Jan 29 to Feb 2, 2020, 1916 people have been evacuated from Wuhan, among them 17 have been confirmed 2019-nCov infected. The infection rate is estimated to be 1.1% (95% CI 0.4%-3.1%) using one group meta-analysis method with random effect model. We then estimated that almost 110,000 (95% CI: 40,000-310,000) people were infected with 2019-nCov in Wuhan around Feb 2, 2020, assuming the infection risk of evacuees is close to Chinese citizens in Wuhan. Conclusions: At the beginning of the outbreak, incidence of NCP may be vastly underestimated. Our result emphasizes that 2019-nCov has proposed a huge public health threats in Wuhan. We need to respond more rapidly, take large-scale public health interventions and draconian measures to limiting population mobility and control the epidemic.