How Vaccines Work

Vaccines are the safest way to achieve herd immunity, or population immunity, to an infectious disease. The concept of herd immunity relies on the idea of limiting the contagiousness of a disease by ensuring that a large part of the community, or the “herd”, is immune or protected. This means that the more people that are immunized, the less that the disease can spread and the safer the community becomes.

To achieve herd immunity without vaccines, people would have to rely on gaining immunity through previous infection. In other words, the disease would have to spread unrestricted through a community until enough people caught the disease and developed long-lasting immunity on their own. However, letting a virus run rampant through a community is both dangerous and unethical. Allowing any disease to run its course without taking safety measures would certainly lead to unwarranted human suffering and death.

How does a vaccine help? Vaccines effectively train a person’s immune system to fight a disease through special proteins called antibodies. Antibodies are important because they help identify and trigger immune responses to foreign invaders in the body. Antibodies also stay in the immune system even after an infection has been eradicated. This means that if the antibodies come in contact with the same infection again, the person’s immune system will know how to properly fight it off.