A Contagion of Disease is a phenomenon of transmission of disease between living beings. The purpose of this brief note is to focus on the characteristics of a contagion as defined in spatial dimensions. A contagion is transmitted from one living being to another by direct contact or contact over distance, through a tiny agent, sometimes identified as a virus.
The possibility that a living being transmits a contagious agent from one to another by direct contact is the first kind of possibility of a contagion. In this case, distance can be assumed to be zero. It is the purpose of this note to focus on the Contagion Phenomenon as it varies with Distance between two living beings. Human contagion caused by contact with infected physical surfaces is not considered here.
The distance at which a contagion can occur, for the case that the virus is coronavirus and the disease is Covid-19, is usually said to be less than two meters in open space. This is why the concept of social distancing has been developed as a protocol to protect people from a contagion.
Therefore, if two living beings, let us say two persons, are distanced at >2mt, it is assumed that contagion would not happen. Let us call this a “reasonable assumption”. They can be at >2mt distance from each other, and no contagion would happen.
Also, three persons or more can share an open space while maintaining the social distancing rule (SDR)>2mt from each other and no contagion would occur between them. Now, if any two of them violate the SDR and one of them is infected while the other is not, then contagion might occur.
Also, anytime the SDR is violated, a high probability is associated with the contagion. This probability is unknown though. This is why this note is purely conceptual. Yet, probability assumptions can be made for the purpose of mathematical modeling.
As a consequence of the above analysis, whenever there is a distance >SDR(=2mt) between only two persons, the space outside the two spheres of radius 2mt with the center in each person is contagion-free space. But if there are three persons in a group and none of them are <SDR apart, then the space outside of the three spheres with radius SDR becomes a contagion-free space. And if two of them are at a distance <SDR, they create a contagion space.
The geometric locus of contagion space defined as a closed space is here defined as a contagion cluster. Space not contained in any contagion cluster is called contagion-free space.
On the basis of the above conceptualisation, any space can be divided into a universe containing two mutually exclusive and exhaustive sets: {A}: Contagion Clusters and {B}: Contagion Free Space. This division is the fundamental idea of the present Space Conceptualisation.
Axiom:
In the context of contagious disease any space an be divided into two sets:
{A}: Clusters of contagion, and
{B}: Contagion-free space, using as a criterion a maximum distance of contagion
Contagion Avoidance
Given a space with presumably no infections, it would be desirable to keep it that way. That is named here Contagion Avoidance.
The SDR provides a strategic tool for Contagion Avoidance. Given a selected space, the first thing to do is to identify sets {A} and {B}. The idea is to keep any set {B} as such, meaning not becoming {A}.
How? By making impossible (theoretically) to arrive at the first infection case that would change the set {B} to a set {A}. How to do that in practice? A practical protocol needs to be created for set {B}. For example, a ‘Contagion Free Space’ might be (theoretically) closed to any external influence that might bring Infection.
A specific case to examine in light of this conceptual framework is Vietnam, which has shown a very small number of little Covid-19 deaths. Why is that? What did they do? Did they set up a strategy of Contagion Avoidance and are keeping their territory as contagion-free space? Probably so. Close attention to this case could bring light to the knowledge of the right prevention of Covid-19.
Another case to know about is Easter Island.
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