Report from MRC Centre for Global Infectious Disease Analysis

estimates 1200-6000 2019-nCoV cases in Wuhan based on confirmed exported cases on international commercial airline flights out of Wuhan

https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Report.pdf

Conclusions

It is likely that the Wuhan outbreak of a novel coronavirus has caused substantially more cases of moderate or severe respiratory illness than currently reported. The estimates presented here suggest surveillance should be expanded to include all hospitalised cases of pneumonia or severe respiratory disease in the Wuhan area and other well-connected Chinese cities. This analysis does not directly address transmission routes, but past experience with SARS and MERS-CoV outbreaks of similar scale suggests currently selfsustaining human-to-human transmission should not be ruled out.

17 January 2020

Imperial College London 

Estimating the potential total number of novel Coronavirus cases in Wuhan City, China

Natsuko Imai, Ilaria Dorigatti, Anne Cori, 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

Correspondence: [email protected] V2 (updated to include second Thai case)

Background 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 [1]. A novel Coronavirus (2019-nCoV) related to the Middle Eastern Respiratory Syndrome virus and the Severe Acute Respiratory Syndrome virus has since been implicated [2]. As of 16th January 2020, 41 cases (including two deaths [3]) have been confirmed in Wuhan City with three confirmed cases in travellers detected in Thailand (2 cases) and Japan (1 case) [4–7]. Most cases have been epidemiologically linked to exposure at a seafood market in Wuhan which has been closed since 1 January 2020 in efforts to contain the outbreak. Although both travellers have a history of travel to Wuhan City, they did not visit the seafood market implicated in the other cases [2]. Using the number of cases detected outside China, it is possible (see Methods) to infer the number of clinically comparable cases within Wuhan City that may have occurred thus far.

Summary We estimate that a total of 1,723 cases of 2019-nCoV in Wuhan City (95% CI: 427 – 4,471) had onset of symptoms by 12th January 2020 (the last reported onset date of any case). This estimate is based on the following assumptions: • Wuhan International Airport has a catchment population of 19 million individuals [1]. • There is a mean 10-day delay between infection and detection, comprising a 5-6 day incubation period [8,9] and a 4-5 day delay from symptom onset to detection/hospitalisation of a case (the cases detected in Thailand and Japan were hospitalised 3 and 7 days after onset, respectively) [4,10]. • Total volume of international travel from Wuhan over the last two months has been 3,301 passengers per day. This estimate is derived from the 3,418 foreign passengers per day in the top 20 country destinations based on 2018 IATA data [11], and uses 2016 IATA data held by Imperial College to correct for the travel surge at Chinese New Year present in the latter data (which has not happened yet this year) and for travel to countries outside the top 20 destination list.

Edited January 17, 20206 yr by niman