Disclaimer: I am not a virologist, a biologist or a doctor. I hated biology at school and that is the very reason that I am an Engineer.
The amount of writeups on SCV2 on the public network is un-imaginable. I have also written a couple of posts on the same. In this post I would like to write more about how the vaccines work. This is for people who dont want to combine the information available on the public network. If readers are ready to go that extra mile, they can piece all this information together. Let us start
About SCV2:
SCV2 is a RNA based virus. That is, the re-production information is stored as RNA. The RNA strand is safely encased in a protein shell with additional protiens, now known infamously as the spike proteins(S protein). The RNA is the blue print which will be understood by the material which makes up the cytoplasm of a cell. On the most simplest side, a cell is made up of a nucleous, surrounded by cytoplasm held together by a membrane. The nucleous contains the DNA which is converted to RNA, which in turn enters the cytoplasm. The code in the RNA is understood in this area. Normally, the information in the RNA is to make proteins. Why should we know this minimal amount of a human cell composition. Without this premise, we will not know how SCV2 multiplies in the human body. The SCV2, to begin with mainly affects the upper respiratory system. You will now ask me why does it not affect other cells. Well, these respiratory cells have a receptor to which the spike protein attaches itself easily. It is like the spike protien knows the language of the receptor on these cells and it does not understand the language of receptors on other cells. The SCV2 attaches itself on to this receptor and by biological magic, the RNA inside the protein casing is released into the cytoplasm in the affected cell. Now, the RNA which enters the cytoplasm is executed by the constituents of the cytoplasm(It is like running a binary compiled program). The main result of the execution is to create one more copy of the SCV2. This then gets out of the cytoplasm and locks with the receptor of the next cell and so on and so forth. What damages this replication does is known to all. Let us not dwell on this. We have discussed issues which might be helpful for us in understanding how the vaccines hope to work against this virus.
About Adenovirus
Adenovirus is a DNA based virus. That is, the re-production information is stored as a DNA safely encased in a protein shell. These viruses are known to be harmless on humans, if affected would result in a cold only. Of course, as with other viruses there have been several mutations.
mRNA based vaccines:
There are two popular vaccines based on this methodology and they are from pfizer and moderna. As we have discussed earlier, the spike protein with the which the SCV2 starts its journey into the human cell, is a very important identifier. This protein is found to be unique. This uniqueness of the protein lends itself to identify the virus. mRNA vaccines work by delivering the mRNA to the cytoplasm of the muscle cells. This mRNA is a compiled program executed by the constituents in the cytoplasm of the cell. The result of the execution is the production of spike proteins. To elicit an immmune response, enough cells should be invaded and the mRNA has to be delivered to the cytoplasm. The mRNA is pure chemistry and can be very well understood by people in that field. The chemical formula is a copy of the chemical formula of the spike protein found in the SCV2. The immune response peaks in about 2 weeks time based on the present dosage. Increasing the dosage would improve the response times, but would also result in such a great immune response that it would start attacking the healthy cells also. This is the reason that the second dose is given after a gap of a month or so. The second jab also helps in creating memory cells which stay in the body for a long time, maybe enough for a lifetime. The optimum dosage has been finalized based on the 3 phases of vaccine development. The medium through which the mRNA is delivered to the cell is though lipid solution which bonds easily with the cell membrane and allows the entry of the mRNA into the cytoplasm. Here we can have issues. One is the allergy of the individual to the lipid solution used to deliver the mRNA. If the person is allergic then the boding does not happen between the lipid solution and the cell membrane which stops the mRNA to enter the cytoplasm. Since the mRNA enters the cytoplasm and does not have to deal with the nucleous it is clear that it does not alter the host DNA contained in the nucleous of the cell.
Adenovirus based vaccine:
The most known ones are the Astrazeneca and the Johnson & Johnson vaccine. Trillions of adenovrirus are cultivated in a controlled lab environment. The DNA of this virus is altered to result in the following
a. The DNA part which allows it to duplicate is edited out. b. The chemically formulated compiled code for producing the spike protein in the form of a DNA is added to the original adenovirus DNA strand. c. Its infecting capablity is intact.
The viruses are then transferred to an injection medium. In summary, live viruses are injected into the human body through the vaccine jab, but crippled as mentioned above. So, if 25 billion viruses are injected, then they stay 25 billion and cannot replicate. Once injected, the adenovirus clings on to a muscle cell and transfers the DNA into the nucleous of the host cell. The vacine makers are telling that though the DNA enters the host cell it does not interact with the host DNA. Once inside the DNA is converted to mRNA and then moves out of the nucleous into the cytoplasm. From here the procedure of making the spike proteins and generation of immune response is the same. There are some issues here. When the live attenuated adenovirus is injected, there are chances that the human body prodcues immune response for the virus itself. This will kill the virus before it delivers the DNA payload. This is the exact reason why the astrazeneca vaccine did not work for people in South Africa and all the doses were returned back. This is because, the people in this country are already exposed to this variant of adenovirus and already have antibodies developed which will kill the virus once they are injected. This vaccine works only if the virus is unknown to the human body. There have also been instances of blood clots and other related issues in some countries while in some countries the issues are minimal in this regard.
De-activated SCV2 vaccine:
This is the most simple and the most straightforward type of vaccine considering the fact that the methodology is used for various classic vaccines like the small pox. So, you cultivate SCV2 in the lab. Totally de-activate them. Put them in and injectible solution. Inject this into the muscle cells. The body will produce immune response to various facets of the virus compostion. So, this seems to be the best possible solution. Yes. However, there are some issues. It is costly to manufacture. It cannot be manufactured quickly in large scale. The quality constraints are very high. Every jab should be free of any live virus, otherwise the result can be catastrophic. The quality procedure should have a testing procedure to ensure that all the batches of the vaccine, every drop of it, does not have any live virus. The most well known is the Covaxin. There are others being used and I am afraid of even naming them since I dont trust them, the trust is lesser than the size of the virus.
Chemically fabricated spike proteins:
This method of preparing the vaccine is the cheapest. The most important one is the one from Biological E. Here the spike proteins are fabricated in a lab. These proteins in an injectible medium is delivered to the muscle cell. The body develops immune response to the spike proteins. Instead of the human body producing the spike proteins and then expecting an immune response, here we are doing the job of making the spike proein in the lab.
The purpose of the vaccines are to produce immune response to the UID of the virus and to ensure that enough memory cells are created which remember this UID and be ready with the necessary immunity response when dealing with a real SCV2.
Thanks to all the virologists and all the hard working health professionals for developing a vaccine in such a short time. Condolenses to all the people succumbing to this virus. Everybody alive, kindly wear your masks properly and try to learn the “mask etiquette” properly. Get your vaccine shots. Dont forget that all the vaccines require a minimum of 2 weeks to create an immune response. The first three days of taking a vaccine shot are crucial. The immune system will be at its most crippled. Kindly stay at home for these three to four days. You might have a light fever. Stat away from alcohol and smoking for a minimum of two months from your second jab.
PS: An example for a virus which alters the host DNA is the HIV