What is in your child’s vaccines and why they are safe?

Written by Inceptive
Estimated reading time: 4 minutes
What is in your child’s vaccines and why they are safe?

The number one priority for every parent is keeping their child safe. From the minute you see that positive pregnancy test, you spend all of your time figuring out how to make sure that your child thrives. At the end of the day - that is what parenting is! But there is often so much information out there, much of it contradictory, and that makes your job as a parent that much more difficult. 


A hot button issue these days is vaccination. In Inceptive’s class, ‘What parents should know about vaccinations’, a pediatrician Dr. Monica Josten, discusses what vaccines are, what is in them, and why they are safe and important for your child to receive.


So, what goes in vaccines? That is the question that most people ask - there has been a lot of misleading information about the ingredients of vaccines, and it is understandable that parents want to know more about what they are exposing their child to. There are five main components to vaccines:

  • The bacteria or virus of interest
  • Adjuvants
  • Stabilizers
  • Preservatives
  • Residuals


Each vaccine contains a bit of the virus or bacteria that it serves to immunize the child against. There are four different types. The first type contains a live, weakened version of the virus, such as the MMR or rotavirus vaccine. These confer lifelong immunity, but are not safe for patients with decreased immune function. Other vaccines contain killed viruses, such as the polio or hepatitis A vaccine. Then there are the vaccines that contain part of the virus (such as hepatitis B) or part of the bacteria (such as PCV). The last three types require multiple doses to get a good immune response. These bits of virus or bacteria generate the immune response, setting your child up to be safe from these diseases. 


That is the part that most of us understand easily - so why are there other ingredients as well? What purpose do they serve? Are they safe? Well, just as you need multiple ingredients to make a delicious cake, you need multiple components to create a safe and effective vaccine. The next component of a vaccine is the adjuvant.


Adjuvants enhance the immune response so that we are able to use less viral or bacterial components in the vaccine. Some examples of adjuvants are aluminum or monophosphoryl lipid A. Many people look at aluminum and wonder how it is safe to include a metal in a vaccine - but the reassuring thing is, aluminum is present in many more things than you might expect, including in breastmilk and formula. If a child gets their full schedule of vaccines, they will receive 4mg of aluminum. If a child is breastfed, they will receive 10mg in just 6 months[1], and they will get almost 40mg if they are fed infant formula[2]. The body efficiently eliminates aluminum from the system[3], so within a day, there is none left. 


Next, vaccines contain stabilizers. These protect the proteins in the vaccine from being broken down during manufacture and transport. This could be a sugar, amino acid, or a protein, such as gelatin. Gelatin is often discussed, as there are some groups that avoid pork products, which are used in the production of gelatin. However, most religious groups don't prohibit its use in vaccines[4], as they are injected, rather than ingested, and are highly purified, making it an essentially different product. 


Then, some vaccines require preservatives, to help keep the vaccine from becoming contaminated. Some examples of these are phenol or thimerosal. Thimerosal has been the subject of a lot of speculation, as it contains mercury. Thimerosal has actually been removed from most vaccines, and the only one that contains it are multi-dose vials of influenza vaccine that are given to older infants and children. Even so, it is still safe for children - in fact, breastfed infants ingest fifteen times more mercury from breastmilk than is in the influenza vaccines[5]! 


Lastly, vaccines might contain residuals. These are egg proteins, because some vaccines, such as influenza are grown in eggs. This used to pose a problem for children with egg allergies. Luckily, due to advances in protein chemistry, children with egg allergies who are over 6 months can safely receive the influenza vaccine[6]. All of these components have been tested in large scale studies, and have been proven to be both safe for children and effective in preventing illness. 


It’s natural that you, as a parent, would want to know more about vaccines. In Dr. Josten’s class, she covers the vaccine schedule, components, and safety in much further detail, allowing you to make an informed decision about what is best for your baby. 

[1] Dórea, José G. Aluminium Concentrations in Human Milk: Aluminium Concentrations in Human Milk: Additional Comments on Exposure Issues in the Neonate. Pediatrics & Neonatology, Volume 55, Issue 2, 81 - 82.

[2] Chuchu, Nancy, et al. “The Aluminium Content of Infant Formulas Remains Too High.” BMC Pediatrics, BioMed Central, 8 Oct. 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3851493/.

[3] “Toxic Substances Portal - Aluminum.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, www.atsdr.cdc.gov/phs/phs.asp?id=1076&tid=34.

[4] Institute for Vaccine Safety - Religious Approval for Porcine-Containing Vaccines, www.vaccinesafety.edu/Porcine-vaccineapproval.htm.

[5] Plotkin, Stanley A., et al. Vaccines E-Book. Saunders, 2012.

[6] “Flu Vaccine and People with Egg Allergies.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 25 Nov. 2019, www.cdc.gov/flu/prevent/egg-allergies.htm#recommendations.

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