This time last year, we had only ever heard of COVID-19 from news articles all the way in China. Who would have known that only a few months later, we too would be the victims of this virus and would be watching the entire world go into lockdown? It’s safe to say that all of us have been waiting and hoping for a way out of it, and it seems like we are finally seeing a light at the end of the tunnel; a vaccine! We are now watching the next chapter of the global pandemic unfold as health authorities around the world are rushing to get their hands on the vaccine. As the time draws closer for us to have access to it, let us take some time to learn a little about what is in them, how and why they work, and why they have been deemed safe for us to take.
To understand how vaccines work, we must first take a look at how our body defends itself from getting infected. Anything which is an ‘enemy’ to our body and has the possibility of causing disease is called a pathogen. It can be anything like a bacteria, virus, fungi or parasite, and its aim is to attack and replicate inside the human body.
The pathogen itself is made up of different parts, one of which is called the antigen. It is unique to each different germ, meaning it acts as an identifier for our body to recognize the invader. For example, the antigen for chicken pox will look different than the antigen for measles. You have probably seen an image of a COVID-19 cell during the past year and noticed the red spikes it has all over its surface. That red spike is actually the antigen for COVID-19.
For our immune system to be able to fight a disease, it must have a corresponding antibody for each different germ it encounters. An antibody is a special protein which works in a similar way to a lock and key. Each antibody must perfectly match the shape of the antigen it wants to fight. We can think of antibodies as ‘soldiers’ in our immune system, each of which is specifically trained to fight one enemy only. This is why our body has thousands and thousands of antibodies.
What happens if our immune system does not have the right antibody? It needs to make a new one! When the immune system encounters a new pathogen that it has never seen before, it responds by creating a new antibody trained to fight it. This process takes a few days, giving the germ time to start replicating within the human body, increasing the risk of our body being overcome by that illness. Once the right antibody is produced and the ‘enemy’ is defeated, the antibody will still be part of our immune system and will be ready to attack quickly if that pathogen attacks again. This process is called immunity, and it is used in vaccines to protect us from certain illnesses. Not all vaccines work in the same way, but we are probably most familiar with Live Attenuated Vaccines and Inactive Vaccines. These work by introducing a weakened form of the pathogen, or a dead pathogen respectively, into our bodies. It is not enough of a dose to make the person sick, but just enough so that our immune system reacts and starts producing the right antibody. That means that this ‘soldier’ will already be part of the ‘army’ and will be ready to attack much faster if the real pathogen shows up in the future. We can think of a vaccine as preparation or training for the immune system to be able to fight that disease.
What about the COVID-19 vaccine? Will we be injected with the virus itself? The two leading vaccines so far (Moderna and Pfizer-BioNTech) are actually of a new type called mRNA vaccines, which have been researched and tested for decades. Messenger RNA (mRNA) is a natural molecule found all over the body and is used for giving instructions. It tells different kinds of cells what to do in order to repair, build and maintain the human body by making new proteins. Within the vaccine, scientists have placed a specific mRNA molecule which tells cells to create the antigen (the red spike) found on the COVID-19 cell. On their own, they are harmless, but they are enough for the immune system to recognize it as an enemy and create the right antibody (or soldier) to fight COVID-19. This means that we will not be injected with the virus itself or any part of it, but just with instructions, or a blueprint for our body to create something which mimics the enemy…kind of like a training dummy. After it is finished using the instructions, the cell breaks down and gets rid of the blueprint so it will not be used again.
Thanks to the hard work and efforts of scientists around the world, we have been able to revolutionize vaccines and medicine in general in just under a year! The process of creating a new vaccine usually takes years, if not decades, to get to the distribution stage. One must also emphasise the fact that for the development of these COVID-19 vaccines, all mandatory and standard stages and scientific evaluation to obtain the necessary approval and authorisation from the respective reputable entities have been adhered to. Over the past months, funding for the sciences has increased exponentially as well as information sharing and collaboration across different laboratories and between scientists themselves. All of these factors have made it possible to accelerate the process and have really proved that the human race can achieve incredible things when we work together!
To read more about vaccines, you can visit:
https://www.who.int/news-room/feature-stories/detail/how-do-vaccines-work
https://deputyprimeminister.gov.mt/en/health-promotion/covid-19/Pages/vaccines.aspx
