Imperial College London researchers estimate there may be over 1,000 cases of the novel Wuhan coronavirus outbreak.
The researchers behind the new report are from the MRC Centre for Global Infectious Disease Analysis, and J-IDEA, the Abdul Latif Jameel Institute for Disease and Emergency Analytics.
The report states 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.
Using the number of cases detected outside China, the reports finds it is possible to infer the number of clinically comparable cases within Wuhan City that may have occurred thus far.
The report estimates that a total of 1,723 cases of 2019-nCoV in Wuhan City had onset of symptoms by 12th January 2020 (the last reported onset date of any case before the report’s publication).
This estimate is based on the following assumptions:
- Wuhan International Airport has a catchment population of 19 million individuals.
- There is a mean 10-day delay between infection and detection, comprising a 5-6 day incubation period 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).
- 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, 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.
The report concludes 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 report is available here