What’s In a Vaccine?


It’s a familiar sight at a doctor’s office. The small clear vial that the doctor dips a syringe into. “Which arm?” the doctor says. It’s a vaccine. Countless people around the world get vaccines every year, whether a long-lasting one or a seasonal one. With vaccines at the forefront of the news with the race to find one for the Coronavirus, it’s clear that a lot goes into a vaccine. But, do you ever think about what literally goes into a vaccine?

Each ingredient in a vaccine serves a specific purpose, and these can be broken into smaller categories. Probably the most important category features those ingredients added for immunity. This includes the main part of the vaccine, the antigen. This teaches the body what to fight and serves as the map for one’s immune response to follow when exposed. The antigen can be an inactivated version of the pathogen or just a genetic code, depending on the vaccine type. People often fear that a vaccine with an inactivated pathogen will give them the disease, but this is completely untrue. Instead, this step helps the body learn what to fight. One of the most intriguing aspects is that only a miniscule amount of the antigen itself is needed to make an effective vaccine. Even just a tablespoon can sometimes make thousands of doses of the vaccine.

Adjuvants are another important part of a vaccine’s recipe. These are substances added to boost the body’s immune response. The antigen may contain a natural adjuvant, but most times, one has to be added. Including one in the vaccine can lower the number of doses needed to make it effective, and can also extend the length of immunity. Newer innovations allow adjuvants to target specific parts of the body to create an even greater boost in protection. One of the most common adjuvants is aluminum, which may sound unexpected, but actually is incredibly beneficial in moderating the release of the vaccine’s active ingredient to extend the immunity. Aluminum is one of the most common naturally-occurring elements in nature, and levels in vaccines are not absorbed by the body, so its inclusion does far more good than bad.

Another category focuses on ingredients added for safety and longevity. It is routine for preservatives to be added before vaccines are distributed. Just like preservatives are added to foods to prevent bacteria growth, they are added to vaccines for the same reason. The growth of bacteria or fungus could be damaging to not only the vaccine, but to whoever receives it. Typically, preservatives are not included in single-dose vials because they are used quickly, but for vials with multiple doses, preservatives are extremely beneficial. Stabilizers are also routinely added to make sure no important ingredient is damaged during production, storage, or transportation. Because vaccines are manufactured so specifically, often even the littlest environmental change can affect a vaccine.

The last major category relates to ingredients remaining from manufacturing. Certain components must be added to help production, but these are removed during the final stages. However, small traces can possibly still be found in vaccines, but they are harmless. Acidity regulators are one of these things. They must be added because antigens must be kept at the right pH levels to prevent distortion that could alter immune response. Antibiotics are added as well to prevent bacterial infections once the vaccine is distributed. Just like how preservatives prevent bacteria growth while awaiting distribution, this helps prevent growth during production. Since bits of the pathogen itself are sometimes used, inactivating ingredients are added to diminish toxicity so the vaccine does not contain a harmful version of a pathogen. And, as the pathogen needs to be cultivated, leftover growth material can find their way into the finished product. But, many organizations, such as the Food and Drug Administration, constantly monitor and regulate vaccines, so know that whatever is in the finished product is safe and approved for humans.