Aluminum is the most abundant metal on Earth. Aluminum can be found in water, soil, plants, our bodies, many food and beverage products, and even air! Aluminum is used in medicine to treat heartburn or certain kidney conditions and is also found in vaccines.

Aluminum in a vaccine is an adjuvant. An adjuvant is a substance that creates a stronger immune response to a vaccine. With the help of adjuvants like aluminum, vaccines need fewer components and, therefore, fewer doses.

The reason why we use adjuvants in vaccines is due to the method of their development. In the past, people used a whole bacteria or a germ, which were weakened or killed. They contained natural adjuvants and helped our bodies produce an immune response that was strong enough. Modern vaccines are different. Instead of a whole germ, we only use its small part (for example, their proteins), which doesn't have enough adjuvants for a strong response needed to protect us from the disease.

Aluminum salts were being used occasionally, starting from the 1930s. Then, it was used in tetanus and diphtheria vaccines, and that is how aluminum's adjuvant effects were discovered. Aluminum salts have been actively used since the 1950s in very small dosages. All vaccines with adjuvants are tested for safety and their effectiveness multiple times and need a license before going public. Even when they're approved, they are still monitored for unusual side effects. So, don't be scared of aluminum in your vaccines - it's actually good for you!