Flattening the Curve
AUTHOR: The Dead Liar
The world is in lockdown and the only people about are health professionals and the police. People who come out of their home for less than emergency are sent back to their homes, sometimes even violently. There is difficulty in buying essentials and a constant fear never leaves the mind of an average person. The professionals, meanwhile, claim that we can fight the disease by staying home. They claim it is to flatten the curve. While most can assume this means to somehow lessen the impact of rampant Covid-19, they do not actually know how. This article aims to clarify the curve and our role to flatten it.
What is the curve?
The curve, mentioned numerously in all media and by the government and health officials, is nothing but a graph of disease and time. Let us start with something simple first and look at the graph below.
The above diagram shows a simple disease correlation with time. One can study it and easily understand that the number of diseased was 1 in first day. It increased to 2 in the second and 3 on the third day. So one can understand that the disease is increasing (by one) per day.
Now let us consider the second graph.
This graph shows that there were 3 diseased on the first day. It decreases to 2, 1 and 0 on second, third and fourth day respectively. thus one can safely say that the disease is being successfully treated.
The progression of disease, however, is not as simple as that. All the diseases usually start with few infected which increases rapidly, stays on the same level for some time then decreases when the treatment procedures or death accelerate. Consider the graph below.
This graph represents a typical disease process. Almost all infectious diseases follow similar graphs. The graph has been broken down into 5 segments for ease of clarification.
Stage a represents the latent [hidden] phase. This means that the disease is there but is not discovered yet. So a low number of diseased cases which corresponds with the incubation period [the time period between the disease entering the body and the body showing symptoms] of the disease. This stage is very important because this is the stage where disease is present but is not seen. It can still transfer from one person to another though. Though it is hard to control, appropriate control on this stage determines how hard the next stage is going to be.
Stage b shows the incremental phase when disease begins to show symptoms. As more and more cases appear, the graph grows steeper. The steeper the segment, the harder it is to control the disease. The steepness, in turn, is determined by how many cases were controlled on first stage.
Stage c shows the plateau phases. It is characterized by a relatively stable of cases. This is because either
- Treatment procedure starts to work in more and more people.
- No. of healthy people in contact with the diseased decrease.
The number 2 point is especially important because if we can limit the number of healthy people contacting the infected, the plateau stage would come much much earlier and the total no of cases would thus be manageable.
Stage d is the treatment phase. This is when the treatment or death of the diseased decreases the number of cases. It is better to have this segment steeper, preferably through treatment than death.
Stage e is the elimination phase when the disease has been successfully controlled and no new cases appear.
Reproduction factor (RF):
Before talking about flattening the curve, a must know term is the reproduction factor (RF). This factor means how many healthy person one infected person can transfer the disease to. For Covid – 19 it is between 2.5 to 3.5 which means that one person can transfer to around 3 healthy people.
Let us assume that there is only one infected person in a country and he is spreading this disease to 3 people per day. The three will infect 3 more each every day. So by day 3, there will not be 6 infected, but 9 and so on. By the tenth day, when the disease hasn’t even shown its symptoms (incubation period for Covid-19 is about 14 days) there will be about 29524 infected (calculated mathematically). Consider this for a while.
Flattening of curve
Let us return back to the topic now that we understand the basics of curve, the role of isolation and why it I so important. Consider the graph below.
The graph shows the relation between diseased of reproduction factor RF=1(a) and RF=2(b) and RF=3(c). It clearly indicated how much different the number of cases go within just 7 days. In a seven day period, for RF=1, the total case would be 7. For RF=2, the total no of cases would be 64 and for RF=3 it would be 729. All this in just one week.
Any decent hospital in the world can take care of 1 case each day. Even if a thousand patients come to the hospital, if only one comes each day, they can be managed with quite ease and the hospital will not be overburdened. However the hospital cannot manage a thousand cases if they come on a single day. By staying home, we are trying to spread the time period for this very 1000 person from a few days to a longer time at least.
Flattening the curve means nothing more than reducing the RF factor from 3 to 2 or less. It can be clearly noted from above graph that decreasing the infectivity from 3 person to just 2 person can reduce the infected by a very significant amount even within a few days time. If the people do not come into contact with others for just a few weeks, those people who could otherwise (unintentionally) infect 3 people would not be able to spread disease that rapidly. When reducing RF from 3 to 2, the number of infected can be reduced from 59049 to just 1023 in 10 day time. This tremendous social responsibility now lies in your hand.