For most people, deciphering a vaccine ingredients chart is no walk in the park.
Especially when substances are described in purely chemical terms like: Di-hydrogen monoxide. Potassium Hydrogen Tartrate. Magnesium Sulfate Heptahydrate. Yikes! Any guesses as to what these ingredients are in layman’s terms?
Hint: you can find them all in houses all over the world!
If you’re thinking we tried to pull a fast one, you’re right. Those intimidating chemical names describe water, cream of tartar, and Epsom salts. Doesn’t seem quite as scary now, does it? This applies to the ingredients in vaccines as well.
For example, ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate) seems a lot less intimidating when you realize it’s just a synthetic lipid – or an oil, essentially – designed to protect the active ingredients of the vaccine.
The first step to overcoming the overwhelm of reading a vaccine ingredients chart is to get informed on common ingredient types and what they’re used for. Luckily for you, we’re doing that right here, right now — so keep scrolling!
In This Article:
- Active Ingredients in Vaccines
- Commonly Used Inactive Ingredients in Vaccines
- Residual Ingredients of Vaccines
The Key Player: Active Ingredients in Vaccines — AKA Antigens
The first thing you should know is this: Vaccines are designed to imitate an infection and therefore push the immune system into defensive action.
By giving your immune system the opportunity to become familiar with a particular infection in very small amounts, it has a better chance of successfully combatting that illness should you be exposed to it down the road.
Hence why every vaccine is crafted around one or more antigens or active ingredients. Antigens are the substance that causes the immune system to respond and defend against the perceived threat. However, not all antigens are direct replicas or duplicates of actual illnesses. In fact, they can come in a few different forms, according to the CDC:
- Weakened or dead viruses/bacteria
- Bits of the genetic material or exterior surface of viruses/bacteria
- Or even bacterial toxins, treated and rendered non-toxic
Every other ingredient in the vaccine is designed to support and protect the antigen, or active ingredient. Antigens are the part that does the hard work — the rest is just the backup. But what vaccine ingredients are considered “backup”, and what do they do to support vaccine efficacy?
Learn More: Seasonal Vaccination: When Should You Get Your Vaccines in 2024?
The Backup: Commonly Used Inactive Ingredients in Vaccines — AKA Excipients
The inactive ingredients in vaccines are known as excipient ingredients. In modern vaccines, these generally fall into one of four categories:
1. Adjuvant Ingredients of Vaccines
An adjuvant is a vaccine ingredient designed to enhance the immune response in the vaccinated individual. Which can, in turn, enhance the efficacy of the vaccine.
Vaccines created from weakened or killed germs typically contain naturally occurring adjuvants. However, since most modern vaccines contain only small parts of viruses and bacteria such as proteins, adjuvants must be added to provoke a significant enough immune response to protect from the original virus.
Historically, the most common adjuvant is aluminum salts.
Aluminum salts have been safely used in vaccines for over 70 years, starting in the 1930s with diphtheria and tetanus vaccines. More recently, newer adjuvants have been developed that allow for a more focused immune response, as well as stronger and longer-lasting disease protection.
These newer adjuvants include options like MF59, an oil-in-water emulsion composed of squalene (shark liver oil). As well as Matrix-MTM, a plant-derived chemical from the soapbark tree and AS01B, also derived partially from the soapbark tree.
Seems a bit less intimidating when it’s all broken down to plain English, doesn’t it? Let’s keep moving and learning, because next comes the stabilizers!
2. Vaccine Stabilizers
Stabilizers are just what they sound like — they help keep the vaccine stable and effective on its trip from the manufacturer to the patient.
But wait! Vaccine stabilizers are not to be confused with preservatives, which in the vaccine context are designed not to extend the lifespan of the vaccine but to prevent contamination in multi-dose presentations. Common stabilizers include gelatin and sucrose – or, in more familiar terms, Jell-O and sugar.
(Hard to complain about that, especially when the amounts are infinitesimal compared to those Rice-Krispie Treats we’ve been eyeing…)
Every vaccine ingredient is there for a purpose, even the Jell-O and sugar. Without these ingredients, the vaccine’s effectiveness would degrade much more quickly. With them, the vaccine stays effective long enough to make it wherever it needs to go to protect you, your community, and your loved ones.
3. Preservatives in Vaccines
To reiterate: Preservatives should not be confused with stabilizers, or vice versa.
While stabilizers are more common, vaccine preservatives typically only appear in multi-dose presentations. Vaccine preservatives prevent contamination and toxins from entering the substance of the vaccine itself — and subsequently, you!
One of the most common preservatives is Thimerosal, or mercury. But before you panic, keep reading — there’s more to the story.
First of all, most vaccines do not contain any mercury at all. Phew! Some multi-dose vaccines (and one type of tetanus-diphtheria vaccine) do contain small amounts of thimerosal, a form of mercury – but it is ethylmercury, which does not cause mercury poisoning and has been deemed safe for use in vaccines.
Double phew! Straight from the CDC, too — the type of mercury used as a vaccine preservative is distinct from the type of mercury that causes mercury poisoning.
4. Residual Ingredients of Vaccines
The final category of vaccine ingredients is residual ingredients.
This can refer to several types of residual ingredients, including cell cultures, antibiotics, and inactivating ingredients. A residual ingredient is something left over from an earlier stage of the production process — sometimes because it is harmless to leave in, and sometimes because it’s harmful to leave out!
For example, residual formaldehyde in a vaccine doesn’t sound so appetizing at first blush, but it serves a very important purpose. Many vaccines contain residual amounts of formaldehyde because it is used to kill or inactivate toxins in the manufacturing process. (This is what is known as an inactivating ingredient.)
“Well why don’t they just take it out?” you might say, “I don’t want any formaldehyde at all, no matter how residual!”
Unfortunately, you’re out of luck. Your body already contains approximately 10x as much formaldehyde as is present in any vaccine. And if you’ve got vintage furniture or fruit around? Forget it! Formaldehyde is a very common chemical that is entirely harmless in small amounts, including the amounts found in vaccines.
But What About Residual Antibiotics in Vaccines? And Residual Cell Cultures?
Residual antibiotics also sound like a potential headache to those with severe allergies or sensitivities — but again, there’s more to the story.
Antibiotics are used during the manufacturing process to prevent contamination from unwanted bacteria, but antibiotics that people are most likely to be allergic to (eg. penicillin) are not used in vaccines. Antibiotics used in vaccine manufacturing include Neomycin, Kanamycin, and Streptomycin.
On the other hand, residual cell culture materials generally refer to remnants of the proteins used to grow enough of the virus or bacteria to make the vaccine.
Influenza and yellow fever vaccines, for example, are grown using egg proteins, and therefore have egg proteins in the final product. Historically, individuals with a severe egg allergy were cautioned against vaccines containing egg protein, but as of the 2023-2024 season, there are no longer any additional precautions recommended.
All residual ingredients are present in very small amounts only and are unlikely to have any effect at all on the patient. Their effect on vaccine safety, efficacy, and longevity, however, cannot be overstated.
Vaccine Ingredients in 2024 — Hard to Spell, Easy to Understand
Being knee-deep in unpronounceable words and scary-sounding terms like “residual cell culture material” can be overwhelming. How is a health-oriented person supposed to figure out what is worth worrying about?!
Here’s where you get to pat yourself on the back — by taking a moment to read this article, you’ve become equipped with a better understanding of what goes into vaccines and why. Good for you! Now you know that, whether it’s to ensure an effective immune response or prevent contamination, no ingredient is superfluous and all have undergone strict safety testing and analysis.
And while this article was designed to serve as a high-level overview of vaccine ingredients and their purpose, not the be-all-end-all of ingredient information, we’ll continue to expand on this topic and take on some more common misconceptions. Subscribe to our blog to stay informed!
