Feasibility of controlling 2019-nCoV outbreaks by isolation of cases and contacts

Joel Hellewell; Sam Abbott; Amy Gimma; Nikos I Bosse; Christopher I Jarvis; Timothy W Russell; James D Munday; Adam J Kucharski; W John Edmunds; CMMID nCoV working group; Sebastian Funk; Rosalind M Eggo

We determined conditions where case isolation, contact tracing, and preventing transmission by infected contacts would be sufficient to control a new 2019-nCoV outbreak in the absence of other control measures. We found that in many plausible scenarios, case isolation alone would be unlikely to control transmission within three months. Case isolation was more effective when there was little transmission before symptom onset and when the delay from symptom onset to isolation was shorter. Preventing transmission by tracing and isolating a larger proportion of contacts, thereby decreasing the effective reproduction number, improved the number of scenarios where control was likely to be achieved. However, these outbreaks required a large number of cases to be contact traced and isolated each week, which is of crucial concern when assessing the feasibility of this strategy. Subclinical infection markedly decreased the probability of controlling outbreaks within 3 months.