Open AccessEstimating the number of undetected COVID-19 cases among travellers from mainland China
Author(s) -
Sangeeta Bhatia,
Natsuko Imai,
Gina Cuomo-Dannenburg,
Marc Baguelin,
Adhiratha Boonyasiri,
Anne Cori,
Zulma M. Cucunubá,
Ilaria Dorigatti,
R Fitzjohn,
Han Fu,
Katy A. M. Gaythorpe,
Azra C Ghani,
Arran Hamlet,
Wes Hinsley,
Daniel J Laydon,
Gemma Nedjati-Gilani,
Lucy Okell,
Steven Riley,
Hayley Thompson,
S Van Elsland,
Erik Volz,
Haowei Wang,
Yuanrong Wang,
Charles Whittaker,
Xiaoyue Xi,
Christl A. Donnelly,
Neil Ferguson
Publication year - 2021
Publication title -
wellcome open research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.298
H-Index - 21
ISSN - 2398-502X
DOI - 10.12688/wellcomeopenres.15805.3
Subject(s) - china , mainland china , covid-19 , china mainland , pandemic , geography , medicine , disease , pathology , archaeology , infectious disease (medical specialty)
Background: As of August 2021, every region of the world has been affected by the COVID-19 pandemic, with more than 196,000,000 cases worldwide. Methods: We analysed COVID-19 cases among travellers from mainland China to different regions and countries, comparing the region- and country-specific rates of detected and confirmed cases per flight volume to estimate the relative sensitivity of surveillance in different regions and countries. Results: Although travel restrictions from Wuhan City and other cities across China may have reduced the absolute number of travellers to and from China, we estimated that up to 70% (95% CI: 54% - 80%) of imported cases could remain undetected relative to the sensitivity of surveillance in Singapore. The percentage of undetected imported cases rises to 75% (95% CI 66% - 82%) when comparing to the surveillance sensitivity in multiple countries. Conclusions: Our analysis shows that a large number of COVID-19 cases remain undetected across the world. These undetected cases potentially resulted in multiple chains of human-to-human transmission outside mainland China.