How are vaccines developed? – blog post 4

My big question is: Are vaccines safe?

This post, I will be looking at how vaccines are developed. Last post, I researched how different types of vaccines work with our immune system to help protect us.

Previously, I learnt about different types of vaccines work in different ways. However, most vaccines have common ingredients. Below I will go over them, and explain why they are essential to help the vaccine do it’s job:

  • Antigens – As previously discussed, most vaccines include a form of antigen, which interacts with our immune system to teach it how to defend itself. This antigen component could likely be a little piece of the disease fighting against, a weakened form of the disease, or an inactive (dead) form of the disease, depending on the kind of vaccine.


  • Preservatives – This protects the vaccine from contamination once the vial is open. Vaccines stored in one-dose vials don’t include preservatives, since they are not left open long enough to be at risk for contamination. However, in some cases, one vial may include enough vaccine for more than one person, in which case preservatives are required. The most common preservative used is 2-phenoxyethanol.


  • Stabilizers – These stop chemical reactions from occurring within the vial, as well as stopping the vaccine from sticking to the walls of the vial. Stabilizers are often sugars, amino acids, gelatin, and proteins.


  • Surfactants – These keep the components of the vaccine mixed together, ensuring that the ingredients don’t separate over time. Surfactants are also often used in foods like ice cream!


  • Residuals – These are ingredients used in the creation of the vaccine that don’t actually play a role in the finished product. Vaccines contain only a very small amount of residual substances, which can be things like egg proteins, yeast or antibiotics.


  • Diluent – This is a liquid used to achieve the right concentration of vaccine before injection. The diluent is often sterile water.


  • Adjuvants – These are substances that make it even easier for our immune system to respond. One of the ways adjuvants can do this is by keeping the vaccine at the point of injection for longer than usual. Another way they do this is by calling the attention of nearby cells. (1) (2)


Vaccine Ingredients: Antigen, Adjuvant, Preservatives, Stabilizers, Surfactants, Residuals, Diluent.

So, what’s the process behind developing these vaccines? Well, there are a couple steps taken to ensure that each vaccine is well made. I’ve tried to explain it as simply as I could to make my post easier to read πŸ™‚

  • STEP 1 – what’s the antigen?

In this first step, scientists work on generating the antigen. During this process, the virus is also grown in a lab. These viruses can be grown inside of cells, or in bio recreators (a tray used for bacteria growing).

  • STEP 2 – collecting the virus

In this step, the virus is removed from it’s growing spot (whether is was in a cell or bio recreator).

  • STEP 3 – purification

In this step, all the residual materials left on the virus from the growth medium are removed, a well as any other parts that aren’t needed. This is also the step in which inactivation occurs if needed.

  • STEP 4 – the extras

In this step is where all of the other ingredients I talked about earlier are added as needed. (3)

  • STEP 5 – phase one trials

This is when the vaccine begins to be tested on a very small group of people. The tests are normally done on young, healthy adult volunteers. These tests are to confirm that the vaccine generates an immune response, confirm it’s general safety, and determine the right dosage required.

  • STEP 6 – phase two trials

In this step, the vaccine is given to several hundred people with the same general characteristics (age, sex, etc.) in order to further test it’s effectiveness and safety. There are usually multiple trials done in this step, in order to test different groups of people or formulations of the vaccine.

  • STEP 7 – phase three trials

In this step, thousands of volunteers are used to test the vaccine. Most are given the true vaccine, but some are given a placebo of sorts. This fake is referred to as a comparator. The group that was truly vaccinated is then compared to the group that received the comparator in order to confirm that the vaccine is indeed effective. (2)

That’s all for this post! Next post, I will be debunking different myths and theories surrounding vaccines. Using the information I learnt this round, I will be looking at the idea that the covid vaccine was too rushed, and comparing the process used normally with the process used for the covid vaccine.

  1. What’s in Vaccines? Ingredients and Vaccine Safety | CDC
  2. How are vaccines developed? (Β  – picture is from this source
  3. How Vaccines Are Made | History of Vaccines

5 Replies to “How are vaccines developed? – blog post 4”

  1. Hi there Jasmine,

    I love your research, super captivating. It’s nice that you described some essential terms; science 9 memory is rejogging.
    For your next post too, I think you may want to look into both inactivated and live/attenuated vaccines!

    For inactivated, as examples:
    Polio (IPV)
    Hepatitis A

    And as for live/attenuated vaccines, as examples:
    Measles, mumps, rubella (MMR combined vaccine)
    Varicella (chickenpox)
    Influenza (nasal spray)

    I’ll certainly be on the lookout for your last post debunking vaccine myths and theories.

    You’re incredible!

    Warm Regards,


  2. Hey Jasmine,

    Amazing post! I really liked the formatting of your information – the brief point form and the separated steps made it really easy for me to follow and understand the content!

    I recently watched this video (linked below) on the process of developing the Covid-19 vaccines. Several people I know initially thought that the Pfizer vaccine was the safest among the others due to its high efficacy rate. This video analyzes how the efficacy rate may not actually reflect what we think because of the differences in their testing periods. Do you believe there is one Covid 19 vaccine that’s better than the other? Let me know what you think!

    Why you can’t compare Covid-19 vaccines:

    Great work! I’ll be looking out for your final round:)

  3. Hi Jasmine!!
    I like the formatting of your post! It is very well detailed and easy to read.

    From all your information, I see that vaccines are safe; however with all the rare cases of blood clots in the recent covid-19 vaccines… do you think it is safe to do so? What is your opinion about that?

    here is a link to a source that can help you with your next post,

    -Lokshana πŸ™‚

    • I’m not too sure yet.. but I think the covid vaccine is safe, despite certain bad experiences. I’ve heard of quite a few other vaccines in the past that a small number of people had bad reactions to, but this didn’t seem to alarm most people, and many got vaccinated despite this. However, covid has become a big point of interest in the media, as we all know, and any information regarding the vaccine is widely spread. I think it’s likely that many people are worried about the vaccine’s side affects because it’s the first time they’re hearing of such a thing, when in reality, it’s not so unusual. Of course, I may be wrong, and I’ll be examining both sides of the argument in my next post!

      • Good point! And I do agree with you! To be honest, I’m also not sure what my opinions are about the COVID vaccines, yet. But you did make a good point about the vaccine not being popular enough that’s why certain people are worried about its side effects.

        I look forward to your next post!! πŸ™‚

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