Vaccines: Separating Fact from Fiction

Understanding vaccine science and tackling misinformation in the digital age

Mar 05, 2025

A Brief History of Vaccines

Even though the practice of inoculation has existed since at least the 1500's, the term vaccine was first used by Edward Jenner in the 18th century (1). The earliest attempt at inoculation probably consisted of intentionally exposing people to smallpox to try to prevent the disease (2). Edward Jenner showed it was possible to prevent smallpox by injecting a person with cowpox taken from the hands of milkmaids. Some 80 years later, Louis Pasteur was able to make a vaccine against fowl cholera, soon after he was able to use post-exposure vaccination to prevent rabies in exposed humans. Following Pasteur's successes, the period from the late 1800's to the current decade saw the development of vaccines for diphtheria, influenza, yellow fever, polio, hepatitis B, pneumococcal pneumonia, measles, malaria, Ebola, COVID-19, and others (1).

What Is a Vaccine?

Britannica defines a vaccine as "a suspension of weakened, killed, or fragmented microorganisms or toxins or other biological preparation, such as those consisting of antibodies, lymphocytes, or mRNA, that is administered primarily to prevent disease"(3). So, a vaccine is, at it's most basic level, a suspension that contains all or part of an infectious organism and is administered to a human (or dog, cat, horse, cow, goat, etc.) to keep that human from getting the disease targeted by the vaccine. Vaccines do this by stimulating the immune system to recognize and to fight diseases.

Types of Vaccines

Modern vaccines fall into the following categories:

A live attenuated vaccine that contains a live pathogen that is attenuated so that it can't cause disease. Example: MMR vaccine
An inactivated vaccine that contains a killed pathogen that can't cause disease. Example: Rabies vaccine
A subunit vaccine that contains only part of a pathogen, usually a protein (an antigen). Example: HPV vaccine
A recombinant vaccine that uses genetic engineering to create antigens. Example; Hepatitis B vaccine
A conjugate vaccine that includes an added component to stimulate better immunity. Example: Pneumococcal pneumonia vaccine
A toxoid that contains inactivated bacterial toxins. Example: Tetanus vaccine
An mRNA vaccine that uses mRNA to produce an antigen. Example: COVID-19 Vaccine
A viral vector vaccine that uses a non-pathogenic virus to deliver viral genetic material. Example: Some COVID-19 vaccines

How Are Vaccines Made?

The initial step in making a vaccine is to generate the antigen to be used. The antigen might be the pathogen itself, or a protein from the pathogen. Viruses and bacteria for vaccines are grown in different ways. Viruses are usually grown in chicken or mammalian cells. Bacteria, on the other hand, are usually grown in some form of medium. The cultures are then stored in a master seed bank that is carefully maintained (4)(5).

In the next step, the antigen, whether whole or part of an organism, must be isolated and purified. The number of steps in this process will vary depending on the type of vaccine (see above), with vaccines requiring recombinant proteins requiring many steps typically (4). After this, adjuvants (which increase the immune response), stabilizers, and preservatives are added. The formulation of vaccines is done in a highly controlled environment to assure that no impurities are accidentally introduced (4). mRNA vaccines require the additional steps of analyzing the genetic sequence of the virus, selecting the desired protein gene, and inserting it into a piece of DNA to allow the production of mRNA strands (6). This description of vaccine manufacturing is inordinately simplified. For more information, see this article and this article.

Successful Vaccine Campaigns

Since their development, vaccines have helped rid the world of diseases that have caused millions of deaths and untold suffering. Smallpox existed for thousands of years, causing rash and high fever. Historically, one third of the people who caught smallpox died. The disease was responsible for the death of at least 300 million people in the 20th century alone. After a global vaccination campaign, the World Health Organization declared that smallpox had been eradicated. Polio, which causes muscle paralysis and potentially respiratory failure, killed 50,000 people in the early to mid 20th century, many of them children. A vaccine was introduced in 1953 which effectively rid the world of polio, decreasing cases by 99% (7). The highly contagious measles virus killed over 2 million people every year before a vaccine was released in 1963. Other notable vaccine successes include:

Tetanus, which saw a 96% reduction in mortality
Diphtheria, which saw a nearly 100% reduction
Ebola virus, with reported vaccine efficacy of greater than 97%
Cholera, which kills many people in poverty stricken areas. WHO aims to significantly reduce cholera cases by 2030
COVID-19, vaccines for which have decreased the severity of the disease
Many others

Vaccine Myths and Conspiracy Theories

In spite of all the good that vaccines have done for humanity since their discovery in the 18th and 19th centuries, many people view them through what could be described as "conspiracy goggles." Where most see vaccines as vehicles for the reduction or even eradication of certain types of disease and suffering, others fear toxic additives, genetic manipulation, or diseases being caused by the very vaccines that are supposed to prevent diseases. A search on public.openmeasures.io highlights public concern about vaccines. The graph below shows search trends for 'mRNA vaccine' on Truth Social:

It shows some weeks with over 1000 hits. This section will cover why misinformation and disinformation about vaccines are so prevalent and common vaccine myths and conspiracies. Hopefully these myths can be dispelled or debunked by providing accurate information.

Why Are Vaccine Myths and Conspiracies So Prevalent?

One reason that vaccine myths and conspiracy theories are so prevalent is an epidemic of misinformation. There are so many social media posts about vaccines that perpetuate myths and conspiracies that the average person is overwhelmed with information. In a culture of ignorance about the science behind vaccines, people can't distinguish what is real and what isn't, and so they pass on sensational stories about the dangers of vaccines, amplifying the problem. As with conspiracy theories in general, they find that it's just easier to believe what they hear than to accept the complexity of the world, and the subject, and try to educate themselves. The COVID-19 Pandemic made matters worse as people lost faith in government authorities and scientists during the often chaotic seeming official responses to the crisis. Among groups already skeptical about vaccines or about the government, the spread of misinformation and disinformation seemed to reach a fever pitch. COVID-19 vaccine myths are discussed in more detail below.

Harmful Additives?

Vaccines contain various ingredients including stabilizers, preservatives, and adjuvants. Several of these additives, such as aluminum, thimerosal, and formaldehyde have been the focus of significant misinformation and disinformation. Thimerosal is a mercury compound that some vaccines contain as a preservative. It has been blamed for causing neurological damage leading to autism and other brain development disorders. A search for the keyword Thimerosal on X(Twitter) done on the day this post was written brings up dozens of posts full of phrases like "Government Coverup!" and "Thimerosal linked to neurodevelopment harm in children." In a 2025 blog post, one writer makes many sensational and largely unproven claims:

The government has long insisted there are no risks with thimerosal, a mercury-based chemical, used in some childhood vaccines in the 1980s and 1990s, and still an ingredient in some shots today.
Numerous studies and scientists have found a heightened risk of brain disorders, including autism, in children who get vaccines with thimerosal.
When autism and other neurological developmental disorders spiked in the late 90s and early 2000s, the government claimed that thimerosal was taken out of all vaccines that children get in 1999 (or 1997, or 2001, depending on the reference). However, that’s untrue.
There’s been a concerted propaganda campaign to mislead the public on scientific links between thimerosal and autism, as well as other neurodevelopmental disorders.

She then goes on to detail a supposed coverup involving the government and the healthcare establishment (8).

The reality is, thimerosal is metabolized to ethyl mercury, which is rapidly excreted from the body. The other form of mercury commonly found in the environment, methylmercury, is toxic and can accumulate in the body and cause harm. Methylmercury is found in some fish (9). The amount of mercury in a given vaccine is so low that a person can get the same exposure level from a can of tuna, and the form of mercury contained in the vaccines is rapidly removed from the body. The FDA did pass a rule removing thimerosal from childhood vaccines in the late 1990's, but since then many studies have shown the chemical to be safe (10). As a result, though, childhood vaccines with the exception of influenza vaccine, do not contain thimerosal. The persistent claims that vaccine additives contribute to autism is discussed below.

Aluminum, once again, is added to some vaccines as an adjuvant to increase the immune response. It serves a purpose in that it makes the vaccines work better. Concerns have been raised in some quarters that vaccines can cause neurotoxicity or abnormal immune responses in humans. As is the case with thimerosal, the amount of aluminum in modern vaccines is too low to cause harm to people. Most is excreted, although a small amount can accumulate in the bones. The amount that actually accumulates is not dangerous and is less than what would come from other sources. Aluminum adjuvants can cause local reactions at the injection sites, and rarely, severe allergic reactions, but there is no evidence of other adverse effects (11).

Formaldehyde is actually used to inactivate viruses and toxins in vaccine production. A very small amount is left in some vaccines. Formaldehyde is actually made in the body during the production of energy and some of the building blocks of life. The amount of formaldehyde in vaccines is far lower than the amount normally made in the human body, and poses no serious risks (12).

Antibiotics can be found in some vaccines as part of the normal production process. These are not the antibiotics typically associated with reactions in children and adults and are present in minute quantities. The antibiotics, including polymyxin B and streptomycin, may be present in undetectable amounts.

Vaccines and Autism

The supposed link between vaccines and autism was first suggested by Andrew Wakefield in a Lancet article 27 years ago. Wakefield claimed that MMR vaccine was linked to autism in children in the UK. The article was later retracted. According to Time Magazine (13)

February 28, 2018 marks the 20th anniversary of an infamous article published in the prestigious medical journal, The Lancet, in which Andrew Wakefield, a former British doctor, falsely linked the MMR (measles, mumps and rubella) vaccine to autism. The paper eventually was retracted by the co-authors and the journal. Wakefield was de-licensed by medical authorities for his deceit and “callous disregard” for children in his care. It took nearly two decades for the UK immunization rates to recover. By the end, UK families had experienced more than 12,000 cases of measles, hundreds of hospitalizations — many with serious complications — and at least three deaths.

Even though the article was based on fraudulent science, the vaccine-autism myth will not go away. The actor Mel Gibson, on his X(Twitter) feed, recently posted journal articles from Mark and David Geier. Mark Geier is a former doctor who, with his son David, has authored several questionable articles linking thimerosal in vaccines to autism spectrum disorder based on erroneous interpretations of data from the Vaccine Safety Datalink. Geier had his medical license revoked for pushing a treatment for autism that was based on junk science. Yet, his articles are still cited repeatedly on fringe science sites and by anti-vaccine enthusiasts on social media (14).

Numerous studies have failed to show a link between thimerosal, vaccines, and autism. For example, a 2007 study published in the New England Journal Of Medicine concluded (15)

The weight of the evidence in this study does not support a causal association between early exposure to mercury from thimerosal-containing vaccines and immune globulins administered prenatally or during infancy and neuropsychological functioning at the age of 7 to 10 years.

Likewise, the Mayo Clinic concluded in 2022:

Vaccines do not cause autism...In April 2015, JAMA published the largest study to date, analyzing the health records of over 95,000 children. About 2,000 of those children were classified at risk for autism because they had a sibling already diagnosed with autism. The study confirmed that the MMR vaccine did not increase the risk for autism spectrum disorder.

The persistent claims that MMR vaccines cause autism as well as the perpetration of other vaccine misinformation have real-world consequences. After the Wakefield article was published, it took decades for the vaccine rate in children to return to normal levels. At the time of writing a measles outbreak in Texas among a largely unvaccinated population has resulted in over 120 cases and the death of one child. Doctors and officials blame vaccine misinformation as a major contributor to the outbreak (16).

Do Vaccines Cause Diseases?

The idea that vaccines cause disease is a common concern but is largely a misunderstanding. Most vaccines contain inactivated or non-replicating components, making infection highly unlikely. In some cases, vaccines can cause mild symptoms resembling the disease they protect against—for example, the chickenpox vaccine may lead to a minor rash, which is a normal immune response, not an actual infection. A more serious problem occurred with the oral Polio vaccine. There were rare cases of polio that resulted from mutation of the vaccine strain. The vaccine was removed from production and is no longer used (17). A common concern is that vaccines can cause autoimmune diseases, including MS, Guillain-Barre Syndrome, Diabetes, and MS. So far, studies have not shown a link between vaccines and autoimmune disease (18). For example, a 2021 study by scientists in Prague, Czech Republic showed no correlation between common vaccines and long-term autoimmune disease. This study did not include some newer vaccines (19). That isn't to say that they can't cause symptoms, but the common symptoms like fatigue, fever, rash, headache, and others are common when the immune system is stimulated and usually resolve quickly.

The COVID-19 Vaccines

The COVID-19 pandemic necessitated the need to produce vaccines at scale to decrease the severity of the disease and the mortality rate. As discussed above, the early spread of conspiracies and large amounts of misinformation created an atmosphere of suspicion around the vaccines and the perpetuation of many false narratives(20). Many widely circulated myths about COVID-19 vaccines include (21):

COVID-19 vaccines cause cancer
COVID-19 vaccines cause heart disease, blood clots, and strokes
COVID-19 vaccines cause infertility
COVID-19 vaccines can change your DNA
COVID-19 vaccines contain microchips

COVID-19 vaccines do not increase the rate of cancer, as shown in studies of large numbers of people. Review of data did not show an increase in stroke risk among vaccinated people. Likewise, the current vaccines do not cause blood clots. One vaccine, the J&J COVID-19 vaccine, caused a clotting disorder in some people and has since been taken off the market. Interestingly, some men did have decreased sperm counts after the vaccine, which was found to be related to fever and is not unusual. Some women experienced temporary menstrual cycle changes, but these did not impact long-term fertility (21).

The idea that mRNA COVID-19 vaccines can change a person's genetic code arose because of misunderstandings about how mRNA vaccines work and how they are produced. As described by the Mayo Clinic (21)

Pfizer and Moderna COVID-19 vaccines only give your cells instructions for how to make a protein found on the surface of the COVID-19 virus. Those instructions, called messenger RNA or mRNA, allow your muscle cells to make the protein pieces and display them on cell surfaces. This causes your body to make antibodies.
Once the protein pieces are made, the cells break down the instructions and get rid of them. The mRNA from the vaccine doesn't enter the nucleus of the cell, where your DNA is kept.

So, the genetic material in the vaccine never has access to the part of the cell where DNA is stored, and is rapidly broken down. mRNA vaccines are a relatively new technology, and the science behind how they are manufactured and how they work is complex and still being refined. In some cases, they have been highly efficacious, while in others, more work needs to be done. In general, though, mRNA vaccines have proven to be safe.

Conclusion

This post is not an exhaustive treatise on vaccine myths, controversies, and conspiracies. It is also not meant to disparage anyone's personal experiences. The author knows one person who had a stroke after and COVID-19 vaccine and several who experienced severe illnesses. The problem is, correlation is not causation, and a single individual or even a small group does not constitute an unbiased study. There are also questions not touched on here. Some groups object to vaccines on religious grounds (like the Mennonites affected by the west Texas measles outbreak), or because of concerns about personal freedoms. This leads to the question about whether the government can and should force people to receive vaccines and shows the difficulty of addressing public health concerns while maintaining personal freedoms. It is important to remember that governments and public health organizations promote vaccines with the goal of increasing immunity among the general population and to protect people who are at risk, such as immunocompromised individuals. That is a subject for another post, though. Hopefully, the information presented here can dispel some of the misinformation and disinformation that exists around vaccines by presenting facts instead of sensational claims.

The Censored State

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