Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (COVID-19)

• DOI: 10.1101/2020.02.14.20023127
• Publication Date: 2020-02-18T03:05:25Z
• Authors: Ruiyun Li; Sen Pei; Bin Chen; Yimeng Song; Tao Zhang; Wan Yang; Jeffrey Shaman
• Keywords: Pandemic; Basic reproduction number; Coronavirus; Contact tracing; 2019-20 coronavirus outbreak

Abstract Background Estimation of the fraction and contagiousness undocumented novel coronavirus (COVID-19) infections is critical for understanding overall prevalence pandemic potential this disease. Many mild are typically not reported and, depending on their contagiousness, may support stealth transmission spread documented infection. Methods Here we use observations infection within China in conjunction with mobility data, a networked dynamic metapopulation model Bayesian inference, to infer epidemiological characteristics associated emerging coronavirus, including contagiousness. Results We estimate 86% all were (95% CI: [82%-90%]) prior Wuhan travel shutdown (January 23, 2020). Per person, these 52% as contagious ([44%-69%]) source two-thirds cases. Our reproductive number (2.23; [1.77-3.00]) aligns earlier findings; however, after restrictions control measures imposed falls considerably. Conclusions A majority COVID-19 implementation January substantially contributed virus transmission. These findings explain rapid geographic indicate containment will be particularly challenging. also that heightened awareness outbreak, increased personal protective measures, restriction have been reductions force infection; it unclear whether reduction sufficient stem spread.