Report 2: Estimating the potential total number of novel Coronavirus cases in Wuhan City, China
Natsuko Imai, Ilaria Dorigatti, Anne Cori, Christl Donnelly, Steven Riley, Neil M. Ferguson
WHO Collaborating Centre for Infectious Disease Modelling
MRC Centre for Global Infectious Disease Analysis, J-IDEA, Imperial College London, UK
On the 31st December 2019, the World Health Organization (WHO) China Country Office was informed of cases of pneumonia of unknown aetiology in Wuhan City, Hubei Province, China . A novel Coronavirus (2019-nCoV) related to the Middle Eastern Respiratory Syndrome virus (MERS-CoV) and the Severe Acute Respiratory Syndrome virus (SARS-CoV) has since been implicated .
As of 4am 21st January (Beijing Time) 2020, 440 cases (including nine deaths) have been confirmed across 13 provinces in China, plus suspected cases in multiple other provinces . As of 9:00 GMT 22nd January 7 confirmed cases in travellers from Wuhan with symptom onset on or before the 18th January were detected outside mainland China in Thailand (3 cases), Japan (1 case), South Korea (1 case), Taiwan (1 case) and the United States (1 case) [4–10]. Chinese authorities have also confirmed evidence of human-to-human transmission, as well as 15 cases in healthcare workers [11,12]. Of these cases, four travelled before exit screening in Wuhan International Airport was introduced on 15th January , three (South Korea, Taiwan, USA) on or after.
Using the number of cases detected outside mainland China with who had disease onset by 18th January, it is possible (see Report 1 ) to infer the number of clinically comparable cases within Wuhan City that may have occurred thus far. Here we update our estimates to account for the additional international exported cases (7 cases).