Letter #4 – COVID-19

10 minute read

Read Part 2 – Test Kits, Cures and Vaccines.

The virus that managed to jump from animal to human sometime back in November / December last year, has managed to bring the entire world to a halt in a matter of weeks. There are just so many aspects to look at this spread that it requires a newsletter in itself.

What is a Virus

Walter Reid was one of the first people to discover a virus back in 1901. Viruses are present across the world, in every species and in the air. We take in and throw out thousands of viruses every day. They are like bacteria but so tiny that if bacteria could see, they would also not be able to see them.

Viruses are not living but they have organic matter than can self replicate. A virus is a shell made of protein that contains genetic material either DNA or RNA. The problem is it cannot replicate alone. It needs to infect another living cell to replicate itself. And as is true for all life around, the only thing every genome is looking to do is replicate.

Cell the smallest living unit whose job is to make DNA, manufacture protein and store resources. Once a virus has overtaken a cell, it uses it to create its genetic material and a protein shell, in essence, creating a new virus. Aim of the virus is the infect a cell and get the replication going.

You can watch this video to understand the difference between a virus and bacteria.

How Coronavirus impacts the body

As explained above a virus is a shell around genetic material and some proteins. It is just on the border of what we will call a living thing.

  • When you come in contact with the Coronavirus and touch your face, it travels from eyes, nose, mouth down towards your internal organs.
  • Lungs are especially hit hard. The virus sits on top of your Epithelial cell(This is the cell lining on the outer part of Bronchitis) and passes the genetic information to the cell.
  • Epithelial is protecting the Alveoli, the actual air sacks that exchange Oxygen with Carbon dioxide within the blood. If this is effected your body will not be able to take in O2 and release CO2.
  • As the virus infects the cell, it passes the information to create proteins and genetic material to replicate. There may be errors in the replication of genetic material, which is what causes the virus to actually adapt to a new host. (Theory of evolution)
  • The cell reaches a critical point and then self destructs. This releases the virus created inside your cell into the rest of the body. Each released virus will go on to another cell and give it the same instructions.
  • Our cells communicate through cytokines with each other. A call is made to get immunity cells to the area where cells are dying to check what is going on. (Immune System)
  • When your immunity cells come to save you, coronavirus causes confusion within them as to which cells are affected and which are healthy. Then Coronavirus goes after your immunity cells and hangs on to them.
  • This causes the body to send more immunity cells to the affected area. While in most cases a good thing but Immunity cells have all kinds of powers to tell other cells how to react and even to kill other cells. Imagine they are the enforcers in your body. If they don’t really know who to kill they may start killing the wrong cells.
  • Neutrophiles are Immunity cells that are good at killing bad cells. Once in large numbers, they start attacking everything around, and end up killing healthy cells along with the already impacted cells. They are just looking to stop the spread of the virus and kill bad cells before they cause more damage.
  • Killer T cells are cells that have the responsibility to primarily kill any cell affected by viruses or cancer inside our body. They detect if a cell is affected and can pass an instruction to self destruct. Due to the confusion, they also start taking down healthy cells along with bad cells.
  • Now if your immune system is strong over time it will fight back, kill the bad cells and keep enough healthy cells around to regrow and start the recovery process. This is what is going to happen in a large number of people who get affected.
  • People who have a weak immune system or have respiratory problems indicating that one of the above is less than ideal in their body, may not be able to fight back. This causes breathing problems and critical patients need respirators to help them breathe. The immune cells have just fought a long battle against the virus and have no energy left to fight another battle.
  • In very severe cases if you lose the outer layer, then the Alveoli is going to be impacted by bacteria in your body. The virus and bacteria that don’t get access to it will now have a free run and block the exchange of O2 and CO2.

Or just watch Kurzgesagt. This person has the most amazing animation based educational content you will find out there.

Origins of Coronavirus

The origins of the Virus have been traced to Wuhan, China inside a Wet market. First known human infection was detected sometime in December. Molecular clock studies traced it back to November since it was first would have been traced inside a human system.

China Wet Markets

Coming back to China Wet Markets. A wet market is a place where Fresh Animals are sold. That means that the animals are alive in the market and are killed once sold. Basically china, in the late 70s during a famine let some farmers hunt Wild animals. They basically told everyone you do what you need to do to survive as we will not be able to provide you with food. As the farmers started hunting wild animals an Industry formed around it. The more the industry grew the more Chinese supported the Industry. Over the last few decades, the industry grew to become a $150 Billion industry. Wet markets were the cause of another famous Virus, SARS. We will come back to the similarity between SARS and Corona.

As the industry grew it moved from small farmers to industry level wildlife hunting. The wet markets became huge which now had hundreds of variety of species from everyday Rabbits, to rare animals including Tiger, Snakes, Bears and everything you can think of. These were sold at an expensive price and the government was happy to let the industry flourish.

The problem with wet markets is, they are a hot zone for the virus. Animals are pushed together, their liquids are all over each other. This gives viruses enough chances to find new hosts, replicate and eventually reach a new genome that will infect human species as well. In the end, we are just part of the complex planetary ecosystem. This also means that wildlife that may have been deep inside jungles, with a virus that may have never come in contact with humans, against which we have no immunity are now brought to the wet market and can feast on the kind of host they are able to survive and flourish in. This is the virus party, trying to look for a new host to make the jump to.

A documentary by VOX pretty much gives a decent insight into China wet markets and the virus.


Coming back to Coronavirus, the official name is SARS-Cov-2 and the disease caused is called COVID-19. It is a completely new virus and we have not seen this virus before. The virus family is Coronaviridae. It is very similar to SARS-Cov (The original SARS virus) from 2002.

Most viruses around are not adapted to using humans as hosts and our immune cells are going to strike them as soon as they enter the system. But given that millions of viruses are replicating outside humans once in a while a virus that copies the genome incorrectly becomes very apt to use humans as the host. Once the virus is able to jump from another host to a human, this virus has the genome that can survive and replicate with the human body. This virus genome is now getting a new host that was unexplored and will now go from host to host as it has found a new ecosystem to thrive inside. This process is the mutation of the virus.

Coronavirus is actually a family of the related viruses with a single strand RNA usually found in mammals and birds. This is generally the largest known genome virus in size (27-34 kilobases) It is 79.5% similar to SARS, and 96% similar to a coronavirus found in Horseshoe bats. We have already found 28 different genomes of this virus. MERS also comes from the same family of viruses.

There are multiple viruses from this family for which our body is immune to. Some forms of the common cold are a result of the virus from this family, just that they have not mutated enough to get past our immune systems.

The above the still just best estimates as of now. Every single day scientists are working hard to figure out the source, how the virus mutated. There are Scientists who believe that it may have been in humans for some time but has just figured out how to jump from a human to human and earlier used to die once it jumped from an animal to human.

Also as with every virus, this one too is mutating fast.

The Spread

Again the virus is still just on the edge of what you will call a living thing. It has protein and genetic material but has no way to do anything really, not even replicate. If it finds no host it will die and disappear.

  • Person to Person –
    • If you are in close contact with an infected person
    • Respiratory droplets (someone around you coughs or sneezes)
  • Spread from contact with contaminated surfaces
    • The virus can survive on surfaces if you touch a surface that has the virus and then touch your face you can get infected.

Symptomatic people ( people who have symptoms of infection) are more likely to spread than people with Asymptomatic people( who don’t show symptoms). But either of the people can spread the Virus. And this is the reason why this virus has spread far more than anything earlier. People who don’t show symptoms are also going to spread the virus. Their immunity may prevent them from going to a serious condition but the virus will find and spread inside another person.


The most common symptoms for Coronavirus are not much different than the symptoms from Common Cold and thus makes it even more difficult to detect and trace.

  • Fever
  • Tiredness
  • Dry cough
  • Difficulty in breathing or shortage of breath
  • Persistent pain or pressure in the chest

It may take up to 14 days to show symptoms, so you may catch the virus and still not know you are infected for two complete weeks. The majority of people who have strong immune systems will recover and until a specialized test for Coronavirus is done, there is no way to tell it is different from the normal flue.

How Fast does it spread

A lot of people are doing a really good job of tracking this on an everyday basis. As this number is changing rapidly it would be better to follow this on the links below. As of today the number of infected and deaths. (March 30, 2020). Realtime links – Worldmeter, New York Times

Total detected infections
Total recorded deaths

China has been heavily criticized for not making this public early on, which led to an outbreak. Given that symptoms take up to 14 days to show, it results in a very high lag time in which an infected person has spread to the virus to others. WHO and other global authorities have also been under criticism for not raising an alarm quickly.

This also comes from the fact that the mortality rate is far lower than the diseases that have been tracked before, and also that most spreaders may not show symptoms or show mild symptoms making it difficult to find the actual number of cases or the seriousness of the disease.

In January it China was on high alert, by February Italy, Iran and South Korea had reached a stage of community spread. By early March it had taken over Europe, UK and by the end of March, the entire world is now on High Alert. Travel services are shut. People are stuck without food, shelter and only essential service in whatever capacity is being run across the world. Welcome to a globalized world with cheaper Air Travel and super connectivity.

One of the prediction models that has been used to understand the spread of the virus is the SEIR model.

S: Susceptible, E: Exposed, I: Infected, R: Recovered.

This is the model based on which we know that we need to flatten the curve. Definitely check the video below to understand the model in detail. It shows you how small changes in variables and which variables completely change how fast the virus will spread and what can we do about it.

Key Takeaways

  • Central locations like schools, supermarkets are going to spread the disease much faster.
  • Changes to Hygiene have a huge impact on slowing down the growth
  • How many people eventually die depends on how much have we been able to buy time.
  • Sooner you can identify and isolate people the quicker you are able to get this under control.
  • If there are enough people out there spreading the virus it will eventually have the same result as not isolating and quarantine, but a small percentage of people left is closer to being able to isolate everyone.
  • Asymptomatic people are a problem, as they are not detected but will spread the virus
  • Social distancing is extremely helpful to slow down the spread but small imperfections prolong the spread over time.
  • All we are trying to do is buy time to isolate every person, find a cure and prepare our health setups to be able to handle it.
  • Travel restrictions are extremely helpful in containing the area of spread. The earlier these are put in the better it is.
  • City centers and central locations are going to spread the virus on an accelerated rate.

If you want to fiddle around with the model yourself and see the results, you can use the following links. Kevin Simler or Geogebra

How to prevent it from spreading

  • Hygiene
    • Wash your hands with soap regularly
    • Sanitise after touching any surface outside your home
    • Stop touching your face
  • Social Distancing
    • Stay at home
    • In case you go out, keep a distance of 2 meters or more between you and other people
    • Avoid Central locations
  • If you are exposed quarantine yourself for up to 2-3 weeks. You may not show symptoms but you will be spreading the virus.
  • If you show symptoms call a doctor.
  • Contact Tracing – Agencies try to retrace the steps of a person to find out early who others may be infected and quarantine them.
  • Wait out for medicine and vaccine to come out.
  • We are trying to buy time to build up capacity for healthcare or find a vaccine. Till then all the steps above help to slow down the pace of spread.

(Visited 412 times, 5 visits today)

One thought on “Letter #4 – COVID-19

Leave a Reply

Your email address will not be published. Required fields are marked *