Oh yeah.. why muscle tissue? Can I offer my fats instead? :D

Ever wonder why we get injected on our arms? I mean, specifically the one near your shoulder bone? In my previous post, I discussed some of the signs and symptoms you will experience after your vaccination. Now, I want to discuss why exactly we choose “muscle tissue” as the perfect site to poke with a needle (yes, vaccine).

But before I compare muscle tissue with fats (yes fats.. Everyone got fats 😀 ), let me discuss first the role of a muscle tissue. Let me introduce you to our first character: Muscle Tissue (I couldn’t think of a great name 😀 )

Muscle Tissue

Now, Muscle Tissue is the right man (or woman) to an important task: to help distribute the vaccine. Our muscle tissue contains and recruits another important group of cells which we call the “Dendritic Cells“. Speaking of, let me quickly introduce you to our 2nd character:

Dendritic Cell

Now Dendritic Cell has another specialized job: to catch all the antigens (bad cells) and stick on their surfaces (the tentacle-like you see in the drawing, which they call dendrites), much like a flag. Just imagine that these sticky cells got a lot of sticky substances all over their bodies. This will probably look like this. In this case, we take covid19 virus as our example (because, yeah why not?):

Dendritic Cell with Antigens

His job is of course tiring. He needs to collect as much antigens as possible. Imagine yourself doing it. Phew! So anyway, what will happen next. Dendritic cell will now bring all these antigens to the Lymph Nodes, where other immune cells are waiting. Just imagine the lymph node as a Great Hall (just like in Harry Potter) where all immune cells meet. And who’s waiting at the Great Hall? T and B cells.

The Great Hall of Lymph Node (and the Immune Cells)

In the lymph node, the dendritic cells will present these antigens to the T and B cells. These cells will then check to see if they recognize these antigens (well, they will recognize it specially when the antigen has already entered our body). The B-cells will then start making more antibodies that is tailor-made for these antigens. So imagine, the moment all the antibodies are manufactured, that’s the time when we can consider that the vaccine worked.

Okay. So this is the reason why we get injected in a muscle tissue. The next question will be, why not in fats? Oh yeah, remember the time when babies got injected in their butts? 😀 Then why can’t we do it now? Maybe… just maybe.. it will be less painful?

Now let’s talk about FATS. Our (wait lemme count first) 7th character (if we include antigen and antibody in the counting). Here is our beloved Fat. Please give a round of applause 😀

Fatty Fat (ugh.. the smudges in my drawing 😦 )

Since all of us have so much fats (I personally will agree to this 😀 ), why not just inject on fatty parts of our body? Here are few facts about fats which I got from the study of Zuckerman 2000:

  1. If you inject the vaccine to your fats, the mobilization and processing of antigens will be slow. This will only mean VACCINE FAILURE. 😦 And we don’t want it, right?
  2. The antigen may also take longer time to reach the circulation after being deposited in the fats. Imagine, the dendritic cell will take his sweet time to collect the antigens, to travel to the Great Hall and to present these antigens to T and B cells. Just imagine if it travels as slow as the sloth (oh yeah, check my other blog post 😀 ).This will only mean, once again, VACCINE FAILURE.
  3. Now since the vaccine will be in the fats for quite some time (cos yeah, slow processing remember?), the enzyme (a substance that is important in so many chemical reactions, including the ones involved in immunity) will be destroyed. So the thicker the skinfold, the slower the vaccine will work.

Let’s again go back to the time when babies got injected in their butts. Scientists and doctors initially thought that it was okay to inject on their buttocks (with so much fats). But then they eventually realized that our buttocks do not contain the appropriate cells to initiate the immune response.

So that is why. 🙂

Okay, I hope you learned something today 🙂 Wohoo! Til then! See you soon!

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