It is believed that the immune system was put into place in the original human body design. The human body’s immune system is comprised of innate and adaptive components.
In an Answers in Genesis article, scientists asked, “Did God create the immune system knowing that we would need it to battle pathogens after the Fall? Creation immunologist Dr. Joseph Francis suggests that rather than viewing the immune system we know today—as a defense system against microbes—think of it rather as a sensory system designed to interact with beneficial microbes.” Further detailed information regarding the immune system can be found in an article written by Dr. Alan L. Gillen and Jason Conrad on January 15, 2014 entitled ‘Our Impressive Immune System: More Than a Defense‘.
Innate immunity is something already present in the body. Adaptive immunity is created in response to exposure to a foreign substance. The innate takes care of things like healing wounds, and the adaptive portion responds to pathogen growth by preventing it or eliminating it.