One or more substances that cause the immune system to fight an enemy. The enemy could be a bacteria, virus, or cancer. The vaccine can be made from a weak form of the bacteria or virus or a part of a cancer cell. This piece of the enemy excites the immune system. The immune system begins to make antibodies (fighter proteins). This means the immune system is ready to act if it is exposed to the full-strength disease. Researchers are trying to make a vaccine that works against breast cancer.
Read more about vaccines to fight cancer.
Audio contributed by: Richard Roundtree