Recently, the Prime Minister of India has announced a 21-days lockdown as a preventive measure against the pandemicCOVID-19.
The period of 21 days was chosen due to public health/epidemiological significance.
Epidemiology is the study and analysis of the distribution, patterns and determinants of health and disease conditions in defined populations.
The decision of 21-days lockdown is supported by scientific data.
The calculations are based on the estimated incubation period of the virus in a human host.
The 21-day quarantine value is derived from interpretations of outbreak data from past and present epidemics and pandemics.
For example, the cases of Spanish Flu and Ebola have been discussed elaborately in the context.
In epidemiological terms, 14 days are of the initial incubation period and adding another week, i.e. 21 days is to ensure that residual infection dies out.
It is estimated that being a new strain of coronavirus, its median incubation period (the time between the entry of virus to the onset of symptoms/ disease) falls within the period of 14 days.
According to a recent study the median incubation period for COVID-19 is just over five days and 97.5% of people who develop symptoms will do so within 11.5 days of infection.
So, the current period of active monitoring (14 days) recommended by the U.S. Centers for Disease Control and Prevention is well supported by the evidence.
Impact of Lockdown:
Lockdown or quarantine is the most effective way of preventing the spread of the infection from those already infected into the community.
This period gives time to convince people of the seriousness of the situation and build positive public opinion, carry out disinfection of all buildings, vehicles and surfaces and allows hospitals to prepare themselves for the next phase of operations.
Maintaining personal hygiene and practising personal distancing are other helpful preventive measures.