Definition of the incubation period for COVID-19 is critical for implementing quarantine and thus infection control . Whereas the classical definition relies on the time from exposure to time of first symptoms, a more practical working definition is the time from exposure to time of first live virus excretion . For COVID-19, average incubation period times commonly span 5-7 days which are generally longer than for most typical other respiratory viruses . There is considerable variability reported however for the late right-hand statistical distribution . A small but yet epidemiologically important subset of patients may have the late end of the incubation period extend beyond the 14 days that is frequently assumed . Conservative assumptions of the right tail end distribution favour safety, but pragmatic working modifications may be required to accommodate high rates of infection and/or healthcare worker exposures . Despite the advent of effective vaccines, further attention and study in these regards are warranted . It is predictable that vaccine application will be associated with continued confusion over protection and its longevity . Measures for the application of infectivity will continue to be extremely relevant.