In the context of vaccines derived from living organisms, which statement is true?

The statement that vaccines can prevent diseases by stimulating the immune response is accurate in the context of vaccines derived from living organisms. Vaccines work by introducing a harmless component or version of the pathogen (such as weakened or inactivated bacteria or viruses) into the body. This exposure prompts the immune system to recognize the pathogen and initiate an immune response, which includes the production of antibodies and memory cells. These memory cells enable the body to mount a faster and more effective response if it encounters the actual pathogen in the future, reducing the risk of contracting the disease.

This process is central to how vaccines confer long-lasting immunity. It is important to note that while they stimulate the immune system, vaccines do not provide immediate immunity; it takes time for the immune system to make and deploy the necessary components to confer protection. Additionally, vaccines can protect against both viral and bacterial infections, contrary to the misconception that they are only effective against viral infections. The statement that vaccines are synthetic compounds is incorrect, as many vaccines are derived from living organisms or their components rather than being purely synthetic.