Vaccine Ingredients are Safe

Vaccine Ingredients are Safe

Vaccines are one of the few most impactful medical solutions to global health. So why are antivaxxers saying they hurt people?

Vaccines: Vac-Gen/Additives in Vaccines Fact Sheet
Additives in Vaccines Fact Sheet
Want to get the facts? Check out the CDC's excellent resource on vaccine ingredients and safety.
Vaccine injuries are extraordinarily rare. Out of the tiny number (0.00145% of vaccinations) of cases, these are only legal settlements, not medically confirmed cases, nor won legal battles.

Learn more about supposed vaccine injuries here (see #2)

In fact, medical malpractice and human error spans all of medicine whether by a needle, a pair of tweezers, or what is typically low risk surgery—so much so that entire industries thrive because of it. So the fact that metal pointy things that cut into our muscle could sometimes create issues is not actually that surprising. It is not uncommon for hospitals to be sued for surgical instruments left in patients for example.

However, you can see how by isolating those cases, one can make a compelling case that vaccines are dangerous. Are they dangerous? I don't know. Are tweezers dangerous?

How antivaxxers manipulate data


There's a lot of slippery slope to go from Al[uminum] in vaccines to health problems. Usually it has something to do with finding Aluminum in the brain of patients of Alzheimers or Autism, but there is a lot in between Al going into the body and it remaining long term in sufficient quantities in the brain.

To better understand this, consider how much is in a vaccine versus a few every day items.

More information about Aluminum in Vaccines

Vaccine Ingredients - Aluminum | Children’s Hospital of Philadelphia
Aluminum is used in vaccines as an adjuvant. Aluminum adjuvants are used in vaccines such as hepatitis A, hepatitis B, diphtheria-tetanus-containing vaccines, Haemophilus influenzae type b, and pneumococcal vaccines.


Formaldehyde is a a certain dose. This is true of basically anything. Formaldehyde is also in vaccines, but in a quantity well below what is safe.

In fact, not only is Formaldehyde safe, but we produce it naturally in our bodies. It is a precursor to a building block for DNA.

Some will argue that everything changes when Formaldehyde is injected in the body. However, as this study shows, when labeling carbon in formaldehyde and injected into cell culture, the DNA building block Adenine is returned with the same labeled carbon. (Source: Patel, et. al. Nature, 548(7669), 549–554 (2017))

As it turns out, the amount of formaldehyde in vaccines is so low, you could reproduce the vaccine spike over what is naturally occurring in your body just by checking if your coffee is too hot.

More information on formaldehyde in vaccines

Vaccine Ingredients – Formaldehyde | Children’s Hospital of Philadelphia
Formaldehyde is diluted during the manufacturing process, residual quantities of formaldehyde may be found in several current vaccines. However, formaldehyde does not appear to be a cause of cancer in humans.


Thimerosal is a favorite target of antivaxxers even though it has already been removed from almost all vaccines. Multi-dose vaccines like the flu vaccine are basically only ones left that even contain it.

As luck would have it, the fact that it was removed has also been used as a guilty plea against vaccines. In fact, the removal was to get people to continue taking vaccines due to the scare.

Antivaxxers also don't seem to understand the difference between ethyl- and methylmercury (etHg and meHg respectively). meHg is commonly in foods and is more toxic than etHg.

Human quantities assume an individual with 5L of blood.


  3. Mercury Factsheet | National Biomonitoring Program | CDC
  4. Mercury Levels in Commercial Fish and Shellfish (1990-2012) | FDA

Ethylmercury, on the other hand, can be broken down by the body easily as long as it's introduced in the body at a safe level.

Usually this information is left out and the focus instead is on etHg, like meHg being a neurotoxin. This sounds pretty scary until you realize that neurotoxicity is based on dosage.

Ethanol is a neurotoxin. It's the type of alcohol found in alcoholic beverage and is produced naturally in some foods. Really, it lives in any yeast habitat and yeasts are everywhere.

Glutamate is a neurotoxin and it's also naturally occuring as a neurotransmitter in all vertebrates.

The CDC has a great resource explaining the history and efficacy of thimerosol in vaccines


To say a little more about thimerosol, it's important to understand how salts differ from their elemental components. To explain, consider how dangerous even a small amount of sodium is when introduced in water:

The exploding, burning, deadly elements that sustain life on earth

Now consider Chlorine, which was used in chemical warfare in World War I under the name "Mustard Gas" due to its yellow color.

Horrendous! We wouldn't turn around and support combining these two ingredients together, would we?

NaCl: Sodium Chloride

Yes, in fact we will because Sodium Chloride is the chemical name for ordinary, natural, non-GMO, vegan, paleo, table salt. It's the same molecule in abundance in the ocean since the dawn of earth and it's not only safe but necessary to sustain life.

Ordinary salt is just one of many examples showing that combining elements to form molecules is not like adding blueberries to pancakes. When elements react, the molecule they form has properties independent from their counterparts.

This misunderstanding is exactly what fuels the thimerosol argument and is compounded by confusing the two different forms of mercury we ingest

Are sandwiches dangerous?

Are vending machines dangerous?

Are coconuts dangerous?

Is being left-handed dangerous?

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This is all to say, it's easy to show a small and misleading subset of data that proves the story you want to tell.

In the mid-1970s, the scare of vaccine safety generated lawsuits and many were awarded damages. Again, just like the world of medical malpractice at large, lawsuit payouts are constant and normal for medical visits spanning far beyond just vaccines. Despite thin evidence to support these claims, the liability on vaccine manufacturers caused some to go out of business thus reducing the availability of vaccines.

To assuage public concern, the US Congress passed the National Childhood Vaccine Injury Act (NCVIA) in 1986 to require better coordination between government health agencies and to provide mandatory vaccine information statements (VIS). This government intervention only fueled the argument that research and data in support of vaccine data is all part of a government conspiracy.

This is the same argument that is made for claims that the Earth is flat by insisting that all space travel was faked.

It is interesting that these two arguments exist side-by-side by the antivaxxer: On the one hand, the government supposedly admits vaccines are dangerous because there is an act called the "National Childhood Vaccine Injury Act" made freely available to the public on government websites. On the other hand, data and conclusions from government agencies on vaccine safety is considered a conspiracy and a coverup by the government. So which one is it? Is the government trying to cover everything up or address public concerns head on with congressional policies to protect the public from one of many tools of medical care?

Vaccine safety is taken seriously and dangers are made transparent

Unfortunately, government agencies are in a lose-lose situation. Like anything in the environment, added to our bodies, or administered in healthcare settings, there are risks, human errors, and reliably some small percentage of injury or death.

By holding vaccine manufacturing and distribution accountable, making these percentages transparent and correcting them as early as possible, it gives antivaxxers more confirmation bias to suggest vaccines are overall dangerous.

Adam Grant

Adam Grant