To start off, it is very important to understand that viruses in general including this novel coronavirus are non-living things. By non-living things mean, outside a host, for example, human beings, they do not survive and are doormat or non-active. Though many people currently still use the term “killing” the virus, it is mostly advisable to refer to a virus outside the human body or a virus that has been dismantled “non-active”. A virus need a living organism such as a human body to survive.
So if viruses are non-active, how does COVID-19 become active in the human body and more importantly, how do they make us sick? This is a question that the majority of people in the non-medical community have been asking since the global pandemic. To explain this, we need to know what the coronavirus is made up of.
The name corona was given to the virus because of its appearance. According to the scientist who termed the virus, under a microscope, the virus resembled a crown. The word virus is a latin word meaning venom and it is explained as very tiny agents that area able to cause infectious disease. Therefore the name “coronavirus”. Even though this virus is new to us, its genetic material (which we will get into briefly) shows that the virus belongs to a family of other coronaviruses known as “severe acute respiratory syndrome” virus also referred to as SARS-COV. Therefore, not to get confused and to be able to differentiate between these viruses, this novel coronavirus is called SARS-COV-2 or COVID-19 where the 19 stands for the years it was discovered.
Structurally, the coronavirus is made up of little more than a single strand of RNA (a bit like half of the ladder-shaped DNA that humans have) covered in a lipid bilayer (which is the outer layer) and protein spikes. So now that we know how they look like, how do they infect us and make us sick, after all, you might be wondering, how much damage can a tiny non-living virus cause?
Inside every human cells, you have a very sophisticated machinery that sustain the cell and makes sure that the cell does it job as instructed. Your cells are designed to work for you however, once the virus is inside your body and in your cell, it uses the spike protein to bind to the host (human) own cells. Like a key placed in a lock. It hijacks your cells and instruct your cells machinery to now work for the virus and make lots of copies of the coronavirus. So instead of your own cells doing what they are supposed to do under normal circumstances, your cells effectively now works for the virus like a factory producing machine. It is interesting to note that even though we say that your cells makes “copies” of the virus, it is not exactly true. Your cells do not makes copies like photo copying a page or scanning a page to produce the same copy. Instead, once the virus hijacks your cells, your own cells makes the three product the virus is made up of (which we mentioned earlier) which is the RNA, lipid bilayer and spike proteins individually which are then assembled later on to make the coronavirus structure. So to put it simple using a car analogy, it’s like making car parts and then later on assembling the car. This explanation is important because this is how mutations occur. During the production of the different parts of the virus, mutation of the virus can occur which can be either advantageous or disadvantageous. For example, the effectiveness of vaccines being produced can be affected. Imagine making a vaccine for one particular strain of COVID-19 and within some few weeks, 30 different COVID-19 strains are identified. This means that people can still get the virus and die from it.
So now, imagine that your cells are now producing thousands of these tiny coronaviruses, what will happen in the cell? Yep, you guessed right. Eventually, the human cell is overwhelmed and it effectively kills itself. Imagine if your boss told you to work three days straight without a break, you will eventually be overwhelmed and have a burnout. This is exactly what happens with your cells. Moreover, the thousands and thousands of coronavirus being produced, even though they are tiny, the human cell will eventually burst open because there are too many coronaviruses in the cells. This burst will cause the thousands and thousands of coronaviruses to flood out and spread to new cells. The coronavirus will then do the same to these new cells but now because there are more of the virus, they will hijack more cells. This process is how they spread and at the same time destroy your cells.
Colourized scanning electron micrograph of human cells which is shown in green and COVID-19 virus which is shown in purple. Whiles some human cells (green) still have their normal round like structure, some of these cells looks deformed which shows that they burst open once they were infected by the coronavirus (purple) and are now dead.