Alliance for Pandemic Preparedness

February 18, 2020

Estimating underdetection of internationally imported COVID-19 cases



  • Researchers estimated that the global capacity to detect imported cases of COVID-19 is about 38% that of Singapore, which has historically had strong disease detection capacity. High surveillance countries have about 40% Singapore’s detection capacity compared to 37% in intermediate surveillance countries and 11% in low surveillance countries. 
  • If all countries had the same detection capacity as Singapore, 2.8 times as many imported cases could have been detected during the study period.
  • Assuming perfect detection in travelers (due to increased screening procedures), the authors estimate that cases in Wuhan may be under-detected by seven fold. They also suggest the plausibility that many undetected cases have been exported to other countries. 

Niehus et al. (Feb 14, 2020). Estimating underdetection of internationally imported COVID-19 cases. Pre-print downloaded Feb 18 from