How does the COVID-19 vaccine work?
Find out everything you need to know about the Pfizer-BioNtech Vaccine
The mega vaccination operation against Covid-19 in Portugal began on December 27, with the administration of the first batch of vaccines, with 9,750 doses of the vaccine developed by Pfizer’s collaboration with BioNTech. This was the first vaccine to be approved by the EMA (European Medicines Agency), already under review of the Modern American Vaccine.
The battle against the world-made Covid-19 now has a new ally, a kind of magic potion that will make our own immune system cells into the elite of intervention teams.
The way the vaccine acts in our body in order to become immunized for Covid-19 is quite complex, involving knowledge of biology, immunology, nanotechnology and military strategy. Here we will address the main aspects of the vaccine, from its complex magic formula, to the point of becoming immune to corona virus.
- The Formula Pfizer-BioNtech
Starting at the beginning, Pfizer-BioNTech’s BNT162b2 vaccine is made up of nanometric particles —a million times smaller than a millimeter. These nanoparticles are lipid pockets, consisting of genetic material. It’s easier to think of these particles as chocolates with stuffing in the middle. The outside keeps the filling intact and safe from the body’s enzymes. The filling consists of a small genetic chain, a messenger RNA molecule, which contains the information needed to produce Corona Virus Protein S. This protein is responsible for binding covid-19 viral particles to our cells, leaving them infected.
- How is the vaccine stored?
These capsules, despite protecting the molecules of the genetic chain, are not indestructible, being one of their weak points at high temperatures. When exposed to room temperature (20°C) for more than 5 days, these capsules are unable to effectively protect the filling, compromising safety and efficacy. That’s why Pfizer and BioNTech have designed some special packages — some containers that, if not opened, keep the temperature inside at -70ºC for 10 days and will be used to transport the vaccine. If vaccines are required for longer, then they should be kept in specialized cooling equipment.
- How is the vaccine given?
It seems strange to think we’re going to give us such a cold vaccine, right? In fact, before being administered, the vials are transferred to normal refrigerators at a temperature between 2ºC and 8ºC to defrost; for a maximum of five days. Alternatively, vials may also be placed at room temperature, but never exceed25°C if the vaccine is applied within a maximum of two hours after the removal of the frozen containers.
After they are thawed, it’s time to prepare the magic potion. In this case, the health professional performs a complex and meticulous protocol. It begins by inverting the bottle up and down 10 times, without shaking, forming a solution of whitish color, similar to an anise liqueur.
Then, very precisely, it inserts 1.8 millilitres of a sodium chloride solution into the original vial using a sterile needle of 21 or narrower caliber, then taking the air from inside the vial. To do this, simply pull the plunger from the syringe until the retaining stopper reaches the 1.8 milliliter mark.
Now we need to mix the ingredients. For this, the bottle is again inverted up and down 10 times, again without shaking. If the diluted vaccine is transparent or has particulate matter, the vial should not be administered to the patient. If you remain whitish and no visible particles, the magic motion is ready. Then just label with the date and time of the preparation and can be administered to the Portuguese.
Despite the preparation the administered dose is only 0.3 milliliters. The administration is done using a sterile needle and syringe and injected into the deltoid, the muscle in the upper arm, responsible for moving it in all directions and covering the shoulder.
- Preparing for battle
Now let’s get into the part that’s more like military strategy. After the vaccine is administered, those very small capsules with their powerful content will prepare our body to face the enemy.
Our cells are made up of a very thin membrane that protects the cellular content of the surrounding environment. These membranes are mostly made up of lipids. This feature allows us to create great affinity between our cells and the capsules of our vaccine, so when the vaccine particles approach the cells, they merge and the filling, the mRNA,enters the cells.
Inside our cells there are small organelles, called ribosomes. These work as a kind of assembly line, at the service of our cells, taking the genetic material of our cells, the well-known DNA, and converting all the information into proteins. The filling of the new vaccine, as we have already mentioned, is the genetic material that encodes for SARS-CoV-2 Protein S. This has a structure very similar to our genetic material, being therefore transformed into Protein S in our ribosomes. These viral proteins will then follow two paths; or migrate to the membrane of our cells and get exposed, or cut into very small pieces and bind to some molecules called HLA – human leukocyte antigen.
In circulation in the bloodstream are white blood cells, also known as leukocytes, cells that function as elite police officers that protect the human body from invaders. When HLA molecules expose proteins that are part of our body, leukocytes recognize them and trigger a war reaction. And the immune system picks up all the weapons to react.
That’s how you prepare the organism for battle. Sergeants, in this case, are cells such as neutrophils, macrophages and dendritic cells, which protect the body from invaders and swallow particles of the S. They are responsible for the side effects reported after vaccination, such as pain at the injection site or fever, for example.
Cytokines are the most powerful weapon in our system. On the one hand, they will help B lymphocytes produce large amounts of antibodies against invasive proteins. Antibodies are another category of weapons designed to have a strong affinity with protein S, preventing SARS-CoV-2 from binding to our cells and infecting us. On the other hand, they will activate a large movement of T lymphocytes,the SWAT force that will identify the infected cells, destroying them by locking the enemy.
This military strategy of the immune system occurs in the first days after administration of the first dose of the vaccine. However, this military plan is not specific to SARS-CoV-2, i.e., it does not confer cellular immunity. This is because, from a certain point in time, the amount of B lymphocytes and T lymphocytes begins to decrease progressively.
The solution is the second dose of the vaccine, which will develop a real military operation: the creation of cellular immunity. 21 days after the administration of the first dose, the body receives the second dose with the aim of further stimulating the creation of an acquired immune response. The amount of these cells increases again and they become more specific, and more efficient, against SARS-CoV-2, remaining on the battlefield for a long time.
These steps develop cellular immunity, which does not depend on antibodies, but rather on the presence of cells that destroy other infected cells. It’s as if the army didn’t need to use such a large arsenal of weapons because it is enough to experience soldiers on the ground —military personnel with specific training against SARS-CoV-2. Immunologists call it adaptive response: cells can react with other invaders, but have a great ability to attack the new coronavirus in particular after first contacting it.
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