Sars-Cov-2 and Covid-19 Without Politics
Sometimes, in late 2019, a new virus, which we now call Sars-Cov-2, launched an attack from somewhere in China—or at least this is how we understand. It attacked silently at first. By silence I mean that no one really understood that this was a new virus; many facilities everywhere thought they were dealing with the flu. After all, this was flu season.
I am not going to touch up on politics and will stick strictly to the virus and the disease it is causing, which is called Covid-19. As I am sure by now you know that it is a corona virus, I am not going to spend too much time on explaining what the virus looks like. It is pretty actually, with spikes.
Looks are deceiving though because it is not a pretty virus though it seems extremely efficient and effective.
Most literature initially discussed the length of time the virus is alive, or what may kill the virus. I feel it is important to clarify: viruses are not alive. The definition of “being alive” involves certain fundamental biological functions, namely respiration (exchanging electrolytes and gases with the external environment as part of feeding), and viruses have no such functions. Probably the most successful strategy for the “survival” of the virus is to not be alive. So when we talk about keeping a virus alive, we really mean “retain its integrity and virility” such that it can cause disease in a new host. A virus cannot have a symbiotic relationship with humans in a classical sense—like bacteria can serve in our gut as fermenting entity, providing us with much-needed short chain fatty acids.
Since viruses are not alive, they only need a host for propagation and provide no nutrients in return. With this said and done, there can be some benefits to viruses, and so symbiosis exists. The human genome contains an amazingly large percent viral genome (8%). This suggests that these viruses are, in some ways, part of us for some reason.
Contagion & Virility
Now that we know that viruses are not alive, we need to understand what contagion and virility means. Contagion is possible by what is referred to as viral shedding. Shedding happens when a virus presses its RNA (or DNA) into a host cell and baby viruses are created by the cell. The moment of the baby viruses release is referred to as shedding. A cell can shed a ton of baby viruses, each of which is capable then to attack another cell and force new shedding.
Before this shedding, a virus may be in a person’s blood for some time and is not detectable by any means. This is part of the incubation period, when the person is already infected but there are no symptoms, and often the virus is not detectable because simply there aren’t enough of them to be detected. Since shedding occurs, this stage is a contagion stage, because viruses can be in just about any body fluid without our knowledge.
Virility is the speed with which the virus is generated and can then be passed to another host. For example, a disease, such as HIV, has low virility because it is pretty much contained in one person and requires direct contact of body fluids with another. As a one-to-one transmission, while the virus may be fatal, the transmission requires a direct contact between participants in some way.
Sars-Cov-2 is a different virus. It transfers easily in the air, by contact, and also it remains “alive” for a long time on certain surfaces, and even in the air. So Sars-Cov-2 has a high virility. As a result, it also has a very high transfer rate. This transfer rate is referred to as R, where R(o) is the general (it should really be original) transfer rate and R(t) is a specific transfer rate at a particular time–I wish there was such as R(g,o) and R(g,t), where g stands for the geographical location. R(t) is seldom, if ever, mentioned, even though it is more important, since in some places—such as Northern Italy, for example–the initial transmission rate of Covid-19 was significantly higher than in other countries, say Iceland, at the same early stage of the disease. So there is no “generic” R(o) only geographically relevant R(o), which also changes with time, so R(g,t). For some odd reason though, the world is only using a general R(o). It is also important to note that R ==> 0 meaning the goal is to eliminate the virus, in which case we have zero infections, so R(o)=0
R(o) and Herd Immunity
At the discovery of the virus—before we knew what we were dealing with—the R(o) of the virus was very high. If R(o) = 1, an in my earlier example of HIV, it is a one to one transmission, so one person transfers the virus to one other person. With Sars-Cov-2, the R(o) in Italy, at the height of the worst transmission time, was over 3 and that represents an exponential increase where the exponent is 3.
1 person transmits to 3, and then each of that 3 transmits to 3, so that’s 9, and each of the 9 transmits to 3 and so that’s 27, so R(o)=3 is x^3 exponential curve of increase. Of course, once a magic number of people are infected, if there are no more people to infect, even the most virulent disease will tend to R(o)=0, since, in time, everyone already had the virus and they are either dead or immune. This is the “herd immunity” of ideal reach.
In a nation where over 10% of the population already has the disease, if R(o) remains 3, herd immunity can be reached amazingly fast—within days, depending on the population size. But this comes with huge risks because of hospital overuse and thus lack of resources to treat the sick. So we need to reduce R(o) to be close to 1 and then to 0 by any means possible. So in comes the flattening of the curve.
Flattening of the Curve and Social Distancing
Most people misunderstand what flattening of the curve means. Think of a balloon that has a certain amount of air you just blew into and closed the balloon at the base so air cannot escape. Now place your hand on the top of the balloon and press gently. You will see the “flattening of the curve” of the balloon but the air will not be squeezed out of it. Now assume that the air in the balloon are all the sick people. So flattening the curve doesn’t mean fewer sick people. It refers to the same number of people being sick but catching the disease at a slower rate. So rather than all people catching the disease in one month, by flattening the curve, the disease-catching time may be lengthened to several months.
To flatten the curve, many measures may be made: closing cities so transmission rate is zero because people are stuck at home, or by social distancing such that they must stay away distant enough to not catch the disease, and also by wearing protective gear that prevents transmission. So far all of these three have been used successfully to flatten the curve—meaning to give more time for the infection to spread and to allow hospital space for each person who needs treatment. Whether the treatment they get in hospitals is a good one, is going to be discussed in another blog later.
My Current Position
Here I wanted you to understand the meaning of R(o), herd immunity, and flattening the curve, since these are often discussed and very often misused and misunderstood. I also wanted to remove politics about the discussion, which is often a confusing factor.
In a future document (hopefully soon) I will detail the virus and the disease itself. It is complex and requires lots of work on my part, but I am working on a lot of other things that have priority, so keep your eyes on my blog!! It shall come! 😊
Comments are welcome as always, and are moderated for appropriateness