Median estimated incubation period of COVID-19 is five days – but can be two weeks
This is a pooled analysis on likely times from exposure to showing symptoms from 181 confirmed cases. It supports the average expected time to symptoms as being about five days and safety after two weeks without contact to other people.
However, as with all averages, the spread (or range) of all results is just as important. This study showed that symptoms are unlikely to occur much earlier but that in rare cases they might take more than two weeks to develop.
In this analysis, the median incubation period was estimated to be 5.1 days (95% CI, 4.5 to 5.8 days), and 97.5% of those who develop symptoms will do so within 11.5 days (CI, 8.2 to 15.6 days) of infection.
Ref: Lauer SA et al. The incubation period of coronavirus disease 2019 (COVID-19) from publicly reported confirmed cases: estimation and application, Annals Internal Medicine. (10 March 2020).