SARS incubation and quarantine times: when is an exposed individual known to be disease free?

The setting of a quarantine time for an emerging infectious disease will depend on current knowledge concerning incubation times. Methods for the analysis of information on incubation times are investigated with a particular focus on inference regarding a possible maximum incubation time, after which an exposed individual would be known to be disease free. Data from the Hong Kong SARS epidemic are used for illustration. The incorporation of interval-censored data is considered and comparison is made with percentile estimation. Results suggest that a wide class of models for incubation times should be considered because the apparent informativeness of a likelihood depends on the choice and generalizability of a model. There will usually remain a probability of releasing from quarantine some infected individuals and the impact of early release will depend on the size of the epidemic. Copyright (C) 2005 John Wiley & Sons, Ltd.