Vaccines – How do they work and are they safe?

Hey guys! It’s Joerel again! Welcome everyone to a new segment of MedicineOnMyMind called Scientific Saturdays where I will be discussing either biological or biochemical processes inside or outside of humans or other organisms. This will be a once a month blog post, but there may be guest speakers whom will write about their own Scientific Saturdays blogs. In any case, we should start off with this first post.

Assuming you have read the title, today’s topic would be vaccines. We’ll be discussing what a vaccine is, how and why a vaccine works, and any dangers in having a vaccine. (‘Dangers’ is in bold because of the stigmas people associate with vaccines.)

What are vaccines?

Vaccines are dead or weak pathogens (which is done caused by chemicals – we’ll be talking about this later) and forces an immune response in your body. This is known as artificial active immunity; you do not physically the disease, but you do become immune to a specific disease by getting a weaker or dead version of the pathogen.

How does a vaccine work?

When a vaccine is injected into your body, there is an immune response to destroy the foreign pathogen. Essentially, a vaccine causes an immune response in our immune system in order to produce T and B Memory cells for that specific disease (or diseases if you have a three in one like the MMR vaccine). By doing so, this causes a quicker immunological response than if the ‘real’ pathogen (which is not weaker or dead) ever enters our body therefore we do not get sick at all and the symptoms are not expressed. The secondary immune response is so fast, if ever the real pathogen enters our body, the immune system would have the antibodies for the specific disease(s) due to the B and T memory cells present in our body.

Okay, but how does the immune system work on vaccines?

Well, when a pathogen first enters your body, your body is not aware that it is there. That is because the pathogen is miniscule compared to the other cells in the body. Nonetheless, a vaccine gives out several dead and weak strains of a certain virus or bacteria. Your immune system tends to use the phagocytes and phagocytosis to get rid of the pathogens. Macrophages, a type of phagocyte, is the first line of defence. A single macrophage can engulf and digest approximately one hundred pathogens. This process is called phagocytosis. What happens is the macrophage engulfs the pathogen via endocytosis, in which the pathogen is trapped in a vesicle called a phagosome. A phagosome would pair up with some lysosomes to form a phagolysosome, where the pathogen is digested but the antigens are not. The antigens are presented on the cell surface membrane of the phagocyte, which turns the phagocyte into an antigen presenting complex (or APC for short).

Another significant APC is your dendritic cells. These cells oversee choosing and picking of T and B virgin cells that reside in the lymph node. Your dendritic cells are important because these cells decide what type of immunological response you have during an infection. Dendritic cells become APCs by taking a sample of the pathogen via phagocytosis. When this happens, the dendritic cell then travels to the nearest lymph node, where it picks out a T virgin cell that has a complementary receptor on its cell surface membrane. When this happens, the T virgin cells become T-Helper cells, which rapid divide through the process of mitosis (proliferation / clonal expansion). These T-helper cells tend to divide into either killer cells that kill off pathogens, more helper cells that produce cytokines and interleukins for the stimulation of phagocytosis in phagocytes, the clonal expansion of B-cells or the stimulation of plasma cells to produce antibodies. Your T-helper cell then travels to the centre of the lymph node, in which they choose a virgin B-cell which has the similar receptor to the T-helper cell. How this happens is the activated T-helper cell signals to the virgin B-cells that has the same receptors to the T-helper cells. (This is a complicated process, so I’ll link to how this process works below, from the National Institution of Health.)[2] Either way, after the correct virgin B-cell has been chosen, the B-cells become activated B-Cells. The activated B-cell can either become plasma cells or the B-cells become B-memory cells, which remembers the specific pathogen that the plasma cells created antibodies for.

In the end, the antibodies produced by the plasma cells help the phagocytes engulf, digest and destroy the pathogen. But what is important is that the vaccine injected caused an immune response to produce T and B memory cells. This means you are immune (for a long while) for the specific disease and will never contract the disease(s) (for a long time or unless the pathogen mutates, so the whole process above must be repeated).

Dangers of vaccines:

Does anyone think vaccines are one hundred percent safe? Let’s talk about that.

You must remember that most vaccines must somehow either weaken the pathogen first, which means there are several chemicals that are used to do so. It would be wise prior to a vaccination to ask what is in the vaccine or to look up some of the ingredients used to make a vaccine. For example, you wouldn’t take a vaccine that had, for a weird example to highlight my point, nuts when you know you have an allergic reaction to nuts.

Most of the time, vaccines have certain chemicals which either prevents the reproduction of the pathogen when it is injected into you body or encourages your immune system to have a stronger response, so you are immune to the disease at a faster rate.

Most common chemicals used in vaccines are:[3]

  • Thimerosal (Ethylmercury) – This is safe, as this is broken down quickly in the body and is different from the ethylmercury found in fishes. Currently, there is no scientific link that this has any harmful effects, and this is ONLY added for the flu influenza.
  • Formaldehyde – While this may dangerous in large doses, a vaccine only contains a small amount of this chemical (0.02mg) and even then, formaldehyde is diluted into smaller amount during the manufacturing process.
  • Aluminium – After six decades of using aluminium, there has been no evidence that this causes any harmful effects on humans.
  • Antibiotics – This is most likely what causes a bad reaction in your body but manufactures of the vaccines ensure a strong antibiotic is NOT used and most of the time, they are reduced so there are negligible amounts in the vaccine.
  • Gelatin – While this is a major cause in causing allergic reactions, the incident rate is significantly small. If you think you or your child would have a severe allergic reaction (meaning if they do suffer from severe allergic reactions) then it is probably wise to choose an alternative method of immunity. Most of the time, this is relatively safe due to a small amount of Gelatin in a vaccine.
  • Monosodium Glutamate (MSG) – While there has been a small minority of short-term reactions, there are no long-term reactions link to MSG. The Food and Drug Administration, The World Health Organisation and the United Nations deemed MSG safe to use. (besides you guys eat some of this as a flavour enhancer in some foods so…)

Now you may think, even after hearing about what happens in your immune system and how relatively safe the vaccines are, that vaccines are completely dangerous, and you don’t want to put yourself or your child in that situation. But you have to ask yourself, am I really protecting me or my child by not having a vaccine? The answer is no.

Do you really think having natural immunity to diseases will somehow be safer than being exposed to a weaker strain or even dead version of a pathogen? Let’s take an example of measles.[4] Measles target your immune system, leaving you vulnerable to a secondary infection. You have the measles spots and pretty much can lead you to death and even if you do survive, your immune system is weak because of the measles virus that destroyed your immune system, so you’re still weak from the initial attack. Contrast that to taking an MMR vaccine, where you do not suffer from that attack and instead become immune without suffering any severe consequences like possible death. (To read up on possible effects, there’s a link on the citation which will lead you to the World Health Organisation’s information of people suffering from mild to severe effects. There is also one for the CDC’s review on vaccines. The numbers are low, but better to see it for yourself).[5] [6]

By not vaccinating, you are risking yourself and everyone else around you. The effect of herd immunity, where much of the population is vaccinated so the disease cannot infect many people to survive and ultimately leading to the extinction of the disease, decreases by not being vaccinated.

Vaccination is a good thing and a right to have. Don’t wait until it’s too late. If you’re travelling to a country where there’s a specific disease that’s prevalent in your area, ensure you get vaccinated for that disease before you travel, so you do get sick during your travels. It is better to be safe than sorry.

Thanks for reading, and I’ll see you next month for another Scientific Saturday.









Leave a Reply

Your email address will not be published.