The Novel Coronavirus, 2019-nCoV, is Highly Contagious and More Infectious Than Initially Estimated

Steven Sanche; Yen Ting Lin; Chonggang Xu; Ethan Romero-Severson; Nick Hengartner; Ruian Ke

The high R0 values we estimated have important implications for disease control. For example, basic theory predicts that the force of infection has to be reduced by 1 − 1 0 to guarantee extinction of the disease. At 0 = 2.2 this fraction is only 55%, but at 0 = 6.7 this fraction rises to 85%. To translate this into meaningful predictions, we use the framework proposed by Lipsitch et al (16) with the parameters we estimated for 2019-nCoV. Importantly, given the recent report of transmission of the virus from asymptomatic individuals (13), we considered the existence of a fraction of infected individuals who is asymptomatic and can transmit the virus (see Supplementary Materials) . Results show that if as low as 20% of infected persons are asymptomatic and can transmit the virus, then even 95% quarantine efficacy will not be able to contain the virus (Fig. 3B) . Given the rapid rate of spread, the sensitivity of control effort effectiveness to asymptomatic infections and the potential of transmission before symptom onset, we need to be aware of the difficulty of controlling 2019-nCoV once it establishes in a new population (17) . Future field, laboratory and modeling studies aimed to address the unknowns, such as the fraction of asymptomatic individuals, the time when individuals become infectious and the existence of superspreaders are needed to accurately predict the impact of various control strategies (9, 17) .