The Science Behind Vaccines


“In 1736, I lost one of my sons, a fine boy of 4-years old, taken by the smallpox in the common way. I long regretted that I had not given it to him by inoculation, which I mention for the sake of parents, who omit that operation on the supposition that they should never forgive themselves if a child died under it; my example, showing that the regret may be the same either way, and that therefore, the safer should be chosen.”

– Benjamin Franklin, Franklin on Franklin.

Franklin would, most likely, be overjoyed to know that in 1980, the world had declared smallpox, the scourge of children since the known beginning of man, eradicated. The effort to eliminate the disease was conducted by agencies world-wide, and was made possible by the use of inoculation (in Franklin’s time) and by the development of the smallpox vaccine in 1796. Inoculation against disease (the purposeful infection of a healthy human being with a small amount of disease) has been documented from as far back as 1661 in the writings of Chinese Emperor K’ang. Inoculation was dangerous in its time but, as stated by Franklin, the alternative would always be worse. Inoculation was used in the early days until 1796 when Edward Jenner successfully found a safer way to protect against disease. Jenner found that cowpox and smallpox were almost biologically identical and that introducing cowpox into a healthy human body would protect the person from contracting smallpox. Benjamin Waterhouse would then make the new smallpox vaccination public in 1800 through an endorsement by then Vice President, Thomas Jefferson.
Since Jenner’s breakthrough, the vaccine has been used to combat disease through current day. The smallpox vaccine was the first, and soon, vaccines were created to help eradicate and lessen the impact of diseases such as: rabies, anthrax, typhoid, cholera, diphtheria, yellow fever, influenza, measles, mumps, rubella, polio, tetanus, hepatitis A and hepatitis B. These diseases once ruined lives and communities throughout the United States and the world. Now, due to science, outbreaks are few and far between (but, since 2000, are becoming more frequent.)
Vaccines reduce the risk of infection by working with the body’s natural immune system to develop resistance to the disease. When a foreign body is introduced, the immune system springs into action. It attacks the infection by throwing whatever it has at it to “see what sticks.” It can take a long time for the body to figure out how to fight a disease. The dangerous part of a virus or bacterial infection is known as the antigen. Should the immune system win, it encodes the victory on a few T-Lymphocytes, called memory cells, to “remember” how to fight that particular antigen in the future.

The Seven Vaccines

A vaccine imitates an infection, providing just enough disease to give the body a blueprint it can use to destroy the disease in the future. Since the body must itself learn how to kill a disease, symptoms may occur. Currently, a vaccine is developed based on how germs of a disease initially infect cells and how the immune system responds. Today, there are seven main types of vaccines:
  • Live Vaccines contain a weakened version of a virus or bacteria that will not cause serious illness in a person with a healthy immune system. These vaccines are highly effective, but not everyone can receive them, such as children with weakened immune systems or those undergoing chemotherapy. Examples: MMR and chickenpox vaccines
  • Inactivated Vaccines are made by killing the germ. Multiple doses are usually necessary to build up and maintain immunity. Example: polio vaccine.
  • Toxoid Vaccines prevent disease caused by bacteria that produce toxins in the body. The vaccine utilizes weakened toxins, called toxoids, to provide the body with a blueprint to kill the toxin. Example: DTaP (diphtheria and tetanus) vaccine
  • Subunit Vaccines only contain parts of the virus or bacteria. Example: pertussis (whooping cough) vaccine
  • Conjugate Vaccines were created to fight a different style of infection. The invading bacteria contain a coating of sugar-like substances, called polysaccharides, that can disguise the antigen (toxin). Conjugate vaccines connect the polysaccharides with antigens to which the immune system responds well. The immune system knows now to effectively react to the polysaccharide coating. Example: Hepatitis B vaccine
  • DNA Vaccines would dispense with all of the infecting virus or bacteria, except for a few parts of the DNA. The DNA strands would instruct the immune system to produce antibodies to the disease all by itself. Currently, DNA vaccines for herpes and influenza are in the testing phases.
  • Recombinant Vector Vaccines use the same idea as the DNA vaccine, with the difference being that these vaccines use a weakened virus or bacteria as a “ride” for the DNA. In essence, scientists can dress up a weaker virus as a debilitating disease by wrapping it in a cloak of DNA. Currently, scientists are producing vaccines for HIV, rabies and measles.
Since discovery, vaccines have been widely effective in stopping the spread of disease in a population. Sadly, measles, mumps and whooping cough have made a comeback in recent years with 90% of new cases presenting in unvaccinated individuals and children. (Measles was declared eliminated in 2000.)
Vaccines not only help the individual, but also the community. Herd immunity protects those individuals that are too weak to get vaccinated from disease. When enough people are vaccinated in a population, a disease cannot gain a foothold and can be eliminated without every single person being vaccinated. It is in this way that the world has effectively eliminated polio and smallpox, and the United States almost eliminated the measles. As fewer and fewer people get vaccinated, herd immunity ceases to exist, making outbreaks far more common, as in what has currently happened with measles and whooping cough.
Each type of vaccine undergoes its own course of manufacturing, but the steps are mostly the same. The end result is something that can help to someday eradicate the most debilitating diseases in our world.
Despite the many accomplishments of vaccination, some people remain skeptical of the benefits. Much like those parents Benjamin Franklin spoke of years ago, some fear supposed side effects of current day vaccines. This fear is understood, but is primarily based upon tenuous correlations and poor scientific design.
Some of the fear of vaccines concerns the added adjuvants, stabilizers and preservatives. Adjuvants are ingredients in a vaccine that create a stronger immune response and help make the vaccine more effective. The most common adjuvant is aluminum – a naturally-occurring element found in almost every medium, including the food we eat. Adults ingest around 7-9 milligrams of aluminum daily. Aluminum is only used in some vaccines and is not present in live vaccines, such as MMR. The only aluminum allowed in vaccines are the aluminum salts: monophosphoryl (a detoxified bacterial component) and squalene (a compound of the body’s natural cholesterol synthesis). A vaccine’s aluminum content is equivalent to the amount contained in a liter of baby formula. Infants typically receive about 4.4 milligrams of aluminum due to vaccines in their first six months. In comparison, breast-fed infants receive on average 7 milligrams of aluminum their first six months. The amount of aluminum in vaccines is safe for infants and adults.
Stabilizers help a vaccine to remain unchanged when exposed to heat, light, acidity or humidity. Common stabilizers are glycine, gelatin, lactose or sucrose, which generally include proteins, amino acids and sugars. They are not toxic or dangerous.
Another additive in vaccine creation is formaldehyde – a fact that may give people pause. Formaldehyde occurs naturally and its use is quite important, as it eliminates harmful effects of bacterial toxins and makes viruses unable to replicate. Formaldehyde is currently present in the flu, polio and DTaP vaccines, but not present in the MMR vaccine. The amount of formaldehyde in the vaccine is less than the amount naturally found in children and less than the amount safely given to animals in research studies. Formaldehyde is easily broken down by our bodies and quickly excreted in urine. The small amount of formaldehyde in vaccines is safe.
The most controversial additive to vaccines during the manufacturing stage is thimerosal, a preservative present in multi-dose vials. When a needle is inserted into a multi-dose vial, it is possible for microbes to contaminate the vial. Thimerosal protects against contamination. The controversy involves the fact that thimerosal contains a small amount of mercury. The type of mercury it contains (in a miniscule amount) is ethyl mercury, which is broken down by the body and quickly cleared out of the bloodstream. As a precaution, thimerosal was issued out of all vaccines in 1999, and now only exists in adult multi-dose vials of the influenza vaccine.
The biggest detractor that causes parents to forgo vaccines, however, is the assumed connection between common day vaccines and autism. There is no proof that vaccines cause autism, not even a correlation. Most advocates for this theory cite one study – now debunked by the scientific community – conducted by researcher, Andrew Wakefield, on behalf of a legal firm looking to sue vaccine manufacturers.
In 1998, Wakefield produced a paper published in Lancet (a renowned medical journal) that suggested the MMR vaccine caused autism. This produced a firestorm of fear heightened by conspiracy theorists and shoddy journalism. An anti-vaccination movement had begun, leading to new breakouts of measles, mumps and whooping cough in the UK and U.S. In 2010, Lancet redacted the paper and Wakefield’s medical license was revoked. Problems with his study that caused the scientific world to ask questions included:
  • The subject sample was small, consisting of only 12 children.
  • The subject sample was not random, but hand-picked with at least five children showing negative developmental signs before the study was conducted.
  • Three of the 12 children chosen were claimed to have autism, but did not.
  • The study included no control group.
  • The children were diagnosed with autism merely a month after getting the MMR vaccine.
  • Multiple scientists have failed to replicate his results.
  • The British Medical Journal found that Wakefield received the sum of $674,000 dollars from lawyers hoping to sue vaccine manufacturers.
Despite the evidence presented, some still fear vaccines solely because of this study. Fear is a strong motivator and fear for your child’s well-being is stronger, still. Regardless, the positive effect of vaccines cannot be discarded. Debilitating disease is now rare instead of rampant. Vaccinations will hopefully evolve to eliminate measles and mumps, hepatitis, HIV and yellow fever. DNA vaccines and recombinant vector vaccines are extremely promising. More study must be done to ensure the safety and success of vaccines. Studies are still being conducted demonstrating that vaccines do not cause autism. The scientific community is moving forward, and someday, the world will be disease free – if the people allow it to happen.

Eight Steps of Vaccination

Vaccines can take up to three years to produce and are typically done in a series of eight steps:
  1. Decide the type of antigen used (this will determine the type of vaccine used).
  2. Generate an antigen.
  3. Release, isolate and collect the antigen.
  4. Purify the Antigen. (Steps are taken to remove many of the vaccine ingredients)
  5. Strengthen the Antigen. (Adjuvant may be added, such as aluminum).
  6. Combine all of the ingredients. (Stabilizers and preservatives may be added in this step).
  7. The vaccine is packaged.
  8. Each lot is tested to ensure FDA standards are met.


All Things Considered. (2010). Scientist: Autism paper had catastrophic effects. NPR. Retrieved from
Baker, J. P. (2008). Mercury, vaccines, and autism. American Journal of Public Health, 98(2): 244-53.
Centers for Disease Control and Prevention. (2018). Understanding how vaccines work. CDC. Retrieved from
Centers for Disease Control and Prevention. (2018). Understanding thimerosal, mercury, and vaccine safety. CDC. Retrieved from
Children’s Hospital of Philadelphia. (2018). Vaccine ingredients-aluminum. Children’s Hospital of Philadelphia. Retrieved from
CNN Wire Staff. (2011). Retracted autism study an ‘elaborate fraud,’ a British journal finds. CNN. Retrieved from
Public Health. (2018). How vaccines work. Public Health. Retrieved from
The College of Physicians of Philadelphia. (2018). The history of vaccines. The College of Physicians of Philadelphia. Retrieved from

Comments are closed.