Why 21 days? What is the significance of this number?
The 21-day quarantine value has been interpreted from data from outbreaks in the past and present.
Such a quarantine period has been discussed even in the context of Ebola . There is a scientific basis and epidemiological meaning to this number.
Its calculations are based on the incubation period of the virus in a human host.
It is the time between the entry of virus to the onset of symptoms.
The first 14 days is observed as the incubation period. The next 7 days is added for the residual infection to die out.
A recent study inferred that the median incubation period for COVID-19 is just over five days.
97.5% of people who develop symptoms will do so within 11.5 days of infection.
Public health experts also say this is the most effective way of preventing the spread of the infection from those already infected into the community.
Apart from the science behind it, a lockdown period creates awareness of the situation.
Disinfection of all buildings, vehicles and surfaces are carried out in this period. This period also allows hospitals to prepare for the next phase of operations