Alliance for Pandemic Preparedness

February 13, 2020

Serial interval of novel coronavirus (2019-nCoV) infections



  • To better understand transmission dynamics, researchers attempted to quantify the serial interval for 2019-nCoV – the time from illness onset in a primary case to illness onset in the secondary case. They compiled a dataset of 30 known pairs of infector-infectee and estimated an average of 2.6 days which is substantially less than for SARS (8.4 days).  
  • When the serial interval is shorter than the average incubation period, it suggests that pre-symptomatic transmission is taking place and could even be more frequent than symptomatic transmission. This analysis suggests that there may be asymptomatic transmission of 2019-nCoV and that further research is needed to confirm.

Nishiura et al. (Feb 13, 2020). Serial interval of novel coronavirus (2019-nCoV) infections. Pre-print downloaded Feb 13 from