Final answer:
A person who cannot fight off a pathogen that has entered his or her body is known as having an immunodeficiency. This condition prevents the immune system from effectively fighting off infections, leaving the individual vulnerable to diseases that healthy individuals can normally resist. Immunization is a key method in building immunity and defending against these pathogens.
Step-by-step explanation:
The name given to a person who cannot fight off a pathogen that has entered his or her body is someone with an immunodeficiency. Immunodeficiency is the condition where the immune system's ability to fight off pathogens is compromised or completely absent. Normally, our bodies can mount a strong defense against enemy pathogens due to our immune system's innate and adaptive components. The immune system includes barriers like skin and mucous membranes as well as cells and proteins that actively combat pathogens. However, if a person has an immunodeficiency, they are at risk for opportunistic infections, which are infections caused by pathogens that a healthy immune system could fight off.
Pathogens such as bacteria and viruses elicit an immune response by triggering inflammation and the creation of memory cells after initial exposure. If the immune system is functioning correctly, subsequent exposures to the same pathogen will trigger a much faster immune response thanks to these memory cells. However, a person with immunodeficiency does not have this robust response and may be unable to fight off the infection, leading to severe health problems or even death.
Immunization is a preventative measure where a person is deliberately exposed to a pathogen to provoke an immune response and the formation of memory cells specific to that pathogen. Immunizations are critical in keeping populations healthy and in keeping the balance in the evolutionary race between humans and pathogens skewed in our favor.