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

Using this dataset, we estimated the basic parameter distributions of durations from initial exposure to symptom onset to hospitalization to discharge or death. Our estimate of the time from initial exposure to symptom onset is 4.2 days with a 95% confidence interval (CI for short below) between 3.5 and 5.1 days (Fig. 1C ). This estimated period is about 1 day shorter and has lower variance than a previous estimate (1). The shorter time is likely caused by the expanded temporal range of our data that includes cases occurring after broad public awareness of the disease. Patients reported in the Li et al. study (1) are all from Wuhan and most had symptom onset before mid-January; in our dataset, many patients had symptom onset during or after mid-January and were reported in provinces other than Hubei province (where Wuhan is the capital). The time from symptom onset to hospitalization showed evidence of time dependence (Fig. 1D and S1). Before January 18, the time from symptom onset to hospitalization was 5.5 days (CI: 4.6 to 6.6 days); whereas after January 18, the duration shortened significantly to 1.5 days only (CI: 1.2 to 1.9 days) (p-value <0.001 by Mann-Whitney U test). The change in the distribution coincides with the period when infected cases were first confirmed in Thailand, news reports of potential human-to-human transmission and upgrading of emergency response level to Level 1 by China CDC. The emerging consensus about the risk of 2019-nCoV likely led to significant behavior change in symptomatic people seeking more timely medical care over this period. We also found that the time from initial hospital admittance to discharge is 11.5 days ( Fig. 1E ; CI: 8.0 to 17.3 days) and the time from initial hospital admittance to death is 11.2 days ( Fig. 1F ; CI: 8.7 to 14.9 days).