Around the globe, health officials are recommending that people who’ve been in a city or region that has a high number of COVID-19 cases should go into a 14-day period of self-quarantine. And for people who’ve been in contact with someone who tested positive for the virus — for example, at school, work or through a social gathering — officials also request that they self-isolate for 14 days.
But what’s the thinking behind 14 days? Why not seven, 10 or even 20 days? The answer comes down to the virus’s incubation period — the time between being exposed to the virus and when symptoms start. Incubation periods vary from virus to virus. People also start to develop symptoms at different rates. Health agencies, from the World Health Organization to the Centers for Disease Control, use data on a virus’s incubation period to set their guidelines for quarantine periods.