THIS SIMULATION IS FOR EDUCATIONAL PURPOSES ONLY! The parameters used and the curves observed are not characteristic of a particular virus. Our goal is to provide teachers with a qualitative tool to illustrate how a virus spreads and how to fight an epidemic.
In no way can this simulation be used as justification or evidence. A simulation is an approximation of reality. The parameters that characterize the spread and the dangerousness of an epidemic are numerous. These parameters are as much scientific as they are social. Each community is therefore different with regard to the spread of the virus and there is no single answer to fight it. The parameters for this simulation are explained below.
In the fight against the spread of a virus, it is fundamental to remember certain scientific facts:
In the absence of a vaccine, victory against an epidemic therefore requires strict individual discipline (hygiene, confinement, quarantine, social distancing), which is very difficult to implement on a societal scale, especially over time.
For the above simulation, we used the SEIR model (Susceptible-Exposed-Infected-Recovered):
Death cases are not considered in this simulation. It constitutes a percentage of the "I" population (< 1% for seasonal flu, > 3% for Covid-19, > 15% for smallpox).
The simulation applies the following algorithm to two fixed populations of 440 individuals who exchange only a few "travellers".
The distance between each individual is calculated. If the distance between two individuals "I" and "S" is less than a certain proximity threshold, we apply a probability P of contagion which moves individual "S" to "E".
In the absence of "barrier gestures", the evolution in the early stages clearly expresses a very rapid exponential growth in the number of infected (I + E). Health policies are desperately seeking to limit this growth in order to protect its health system. However, an exponential function grows so fast that decisions must be made very quickly.
Political measures are necessarily collective because the presence of a single "I" individual can, over time, contaminate the entire population. This may involve vaccination, containment, or quarantine of all travellers.
This educational simulation allows certain qualitative conclusions to be drawn :
The last point explains the difficulty for governments to organize a "de-confinement".
Move the cursor over the curve to replay the epidemic sequence.