Disclaimer: The following article is oversimplified and some analogies are used for the non-technical readers. Reader’s discretion is advised.
Background: how viruses work/replicate?
Viruses are technically non-living organisms which do not have metabolism and do nothing on their own except wander around randomly, until they stumble upon a living organism that can help the virus replicate.
Viruses are simple structures which has an outer covering called a capsid and a tiny bit of genetic material (DNA/RNA) which helps it replicate. Viruses are very small and usually around hundred times smaller than a bacteria.
Viruses infect a living organism called host such as bacteria, humans and animals; enters host’s cells and use cell’s resources to make copies of itself. When the cell is overloaded with the new copies, its bursts open and releases the viruses, which again wander around until they find a new host.
What is a conventional vaccine? : The Vaccine Analogy
Viruses have caused massive deaths in all civilisations throughout the history of mankind. Small pox, caused by a virus called variola major /minor has resulted in over 500 million deaths over the century of its existence. Thanks to the discovery of vaccines, many such diseases have been under control or have been completely eradicated.
Earliest practice of vaccination was a type called variolation for immunisation against smallpox and was practiced in China, India and parts of Africa.
The current know form of vaccine is to introduce a weak form of the virus or bacteria, such as half-killed virus, broken pieces of the bacteria or a fragile cousin of the virus. This allows the immune system to recognise special parts of the organism and prepare a defence strategy against it.
Assume your immune cells are like police. Viruses and bacteria are like criminal gangs in stylised cars doing crimes. If the police do not know that those people are criminals and all the strong criminals come out at once, the police force will be overwhelmed.
Here comes the beauty of vaccines. Now assume two criminals of that gang, in stylised red cars driving badly were caught by the police (i.e, referring to vaccines introducing weak form of virus).
The police will now gather all the nitty-gritty information of these gang members like gang logos, style, weapons and features of the car including the car logo, seat belt, tyres, engine, seats etc.,
The information is now passed to the police headquarters and they prepare strategies on how to identify and catch the criminals.
They make one strategy for each aspect of information like one strategy for car logo, one strategy for car spoiler, and one for the gang logo and so on.
This is a very resource intensive method. Expand this for hundreds of criminal gangs and members in each.
What is mRNA vaccine?
As opposed to conventional vaccines, the mRNA are new and specific type of vaccines that focus more on the specific attribute of the organism like the colour of the car in our previous analogy.
DNA is like an encyclopaedia for all functions of a cell or organism. For example, the DNA is book of all cooking recipes in the world and when you want to make chocolate cake, you retrieve the ‘mRNA’ recipe for that cake. The mRNA recipe will have specific instruction only for the cake.
The mRNA vaccines for COVID-19 are designed to target the ‘Spike’ protein of the virus, which it uses as a “duplicate locksmith’s key” to enter into your “locked” cell.
Which type of vaccine is better? Pros and cons
Frankly, the short answer is both are better. Vaccines of any type help the body create a defence strategy (how to make antibodies against pathogen) and force it to remember (via memory T-cells, a subtype of your white blood cells).
When the actual pathogen (disease causing organism) attacks you, the body knows exactly how to deal with it. In some cases, the memory of these strategies are for life-time for example polio vaccine.
Immune response or how our body deals with pathogens is a very complex study on its own and scientists are still discovering new things about them every day.
For the purpose of this article, we shall explore few gross oversimplified differences using analogy (without jargon).
Multiple defence strategies against the same pathogen:
With conventional vaccine, when the stylised car enters the highway, police in monster trucks crush them up and bring multiple identifying pieces of the car like tyres, car logo, spoilers, etc., which is now used as identification for the defence strategy
While, mRNA vaccines on the other hand, receive instructions and make strategies against ‘Red car spoilers’ only and not against car tyres, logo or type of seats.
This might seem that mRNA vaccines are not as versatile as the conventional vaccine, but they are very effective in specific disease cases.
For example, assume you know the criminal gang uses a scorpion logo on their car spoilers. Then a defence strategy can be made to identify only scorpion logos and save valuable resources.
Similarly, for Covid-19, when we know the ‘Spike’ protein is the prominent feature, our body does not need to spend valuable resources making antibodies against other non-prominent proteins.
Balance between resources and versatility of responses: A double edged sword
Our bodies are designed to save energy and nutrients and considers them valuable resources. Our body always deals with the dilemma of whether or not to spend valuable resources on a task.
Sometimes the criminals turn out to be very intelligent and may change the colour of the car spoilers which is now a purple stylised car. This is called a variant for example Alpha variant, Delta variant or Omicron variant of Covid-19.
For this reason, the conventional vaccines have an advantage as they will have already prepared additional defence strategies as back up.
Risk of messing with the ‘DNA’ encyclopaedia- VERY RARE PHENOMENON!
Conventional vaccines for viral diseases, very rarely may carry a risk of genome integration. As previously discussed, viruses carry genetic material within them. When conventional vaccines introduce a weakened virus or a fragile cousin, the genetic material in the virus may cause disruption to our cell’s DNA or RNA
From our previous recipe analogy, weak viruses are like pots of ink and when they fall on the recipe for the chocolate cake and blacken out what is written on it, you will not be able to make a cake. Even more damaging if the ink falls on the ‘DNA’ encyclopaedia, then many recipes will be damaged.
However, mRNA vaccines are relatively safer, since they do not have any parts of virus, they do not have the above stated risks. mRNA vaccines only make fake copies of red car spoilers with scorpion logo to train the police and nothing more.
Additional considerations: the logistics
Now that we have covered how vaccines work in the body, we will explore few aspects outside the body.
- It is scientifically, logistically and technically very hard to make mRNA vaccines (as of now) compared to conventional vaccines, as mRNA vaccines are relatively new technology.
- mRNA vaccines are harder to produce in large scale and difficult to store and transport as they are to be kept at freezing temperatures at all time (except before injecting into the body).
There are lots of misconceptions, conspiracy theories and negative emotions in some people against vaccines. Please do remember that human life expectancy has dramatically increased over decades, thanks to rapid medical advancement. These misconceptions do cause significant hurdles to the medical advancement.
In conclusion we would like to say,
Vaccines are like helmets. Helmets do not prevent an accident but saves your head from it, similarly vaccines do not prevent pathogens from entering the body, they save you from severe disease and death.
Dr. RC
Sources
- Schlake, T., Thess, A., Fotin-Mleczek, M. & Kallen, K. J. Developing mRNA-vaccine technologies. http://dx.doi.org/10.4161/rna.22269 9, 1319–1330 (2012).
- Smallpox: The Death of a Disease: The Inside Story of Eradicating a … – D. A. Henderson, M.D. – Google Books. https://books.google.ie/books?id=1u7Xw5i7Ky0C&pg=PA12&redir_esc=y#v=onepage&q&f=false.
- Doerfler, W. NC-ND license Adenoviral Vector DNA-and SARS-CoV-2 mRNA-Based Covid-19 Vaccines: Possible Integration into the Human Genome-Are Adenoviral Genes Expressed in Vector-based Vaccines? (2021) doi:10.1016/j.virusres.2021.198466.
- Rouf, N. Z., Biswas, S., Tarannum, N., Oishee, L. M. & Muna, M. M. Demystifying mRNA vaccines: an emerging platform at the forefront of cryptic diseases. https://doi.org/10.1080/15476286.2022.2055923 19, 386–410 (2022).