What is a vaccine usually composed of?

Question

Quizplus · Accepted Answer

A vaccine is typically composed of inactivated or weakened disease-causing microbes or parts of microbes, such as proteins or sugars, that stimulate the immune system to produce a response without causing illness. The response leads to the production of antibodies that recognize and attack the actual infectious agent if and when the person is exposed to it in the future. Macrophages and antibodies may be involved in the immune response to a vaccine, but they are not the components of the vaccine itself. Hormones do not directly boost immunity.

What Is a Vaccine Usually Composed Of