There are many people who are allergic to a large amount of substances, and those substances could be found in the vaccinations they receive. One substance found in a vaccine is aluminum; aluminum acts as an adjuvant, which makes the body react to the vaccine faster. Antibiotics are another substance found in some vaccines. Some people are afraid there are antibiotics in the vaccine they are allergic to so they choose not to get vaccinated. Most of the time if there are antibiotics found in vaccines there is either a small amount or it can hardly be traced. Antibiotics are used in the vaccines to assure there is no bacteria that grows during manufacturing. However, not all common antibiotics people are allergic to are used in vaccines.