Evidence for transmission of COVID-19 prior to symptom onset
- University of British Columbia, Canada
- Simon Fraser University, Canada
- National University of Singapore, Singapore
- National Institute for Public Health and the Environment, Netherlands
- Leiden University Medical Center, Netherlands
Abstract
We collated contact tracing data from COVID-19 clusters in Singapore and Tianjin, China and estimated the extent of pre-symptomatic transmission by estimating incubation periods and serial intervals. The mean incubation periods accounting for intermediate cases were 4.91 days (95%CI 4.35, 5.69) and 7.54 (95%CI 6.76, 8.56) days for Singapore and Tianjin, respectively. The mean serial interval was 4.17 (95%CI 2.44, 5.89) and 4.31 (95%CI 2.91, 5.72) days (Singapore, Tianjin). The serial intervals are shorter than incubation periods, suggesting that pre-symptomatic transmission may occur in a large proportion of transmission events (0.4-0.5 in Singapore and 0.6-0.8 in Tianjin, in our analysis with intermediate cases, and more without intermediates). Given the evidence for pre-symptomatic transmission it is vital that even individuals who appear healthy abide by public health measures to control COVID-19.
Data availability
Data are available on github at github.com/CSSEGISandData/COVID-19. Code to produce all analyses is also available there. Source data files of the Singapore and Tianjin clusters have been provided.
Article and author information
Author details
Funding
Government of Canada (Canada 150 Research Chair program)
- Caroline Colijn
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Marc Lipsitch, Harvard TH Chan School of Public Health, United States
Version history
- Received: March 23, 2020
- Accepted: June 21, 2020
- Accepted Manuscript published: June 22, 2020 (version 1)
- Version of Record published: July 28, 2020 (version 2)
Copyright
© 2020, Tindale et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Evidence for transmission of COVID-19 prior to symptom onset
eLife 9:e57149.
https://doi.org/10.7554/eLife.57149
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