Final answer:
Administering childhood immunizations is the nursing action that protects the patient as a susceptible host in the chain of infection, by reducing their susceptibility and providing long-term immunity against infectious diseases.
Step-by-step explanation:
The nursing action that protects the patient as a susceptible host in the chain of infection is administering childhood immunizations. By vaccinating individuals, especially children, we reduce their susceptibility to infections, effectively breaking the chain at the host level. Immunizations are a preventative strategy to bolster the immune system against potential infectious agents it may encounter. Unlike wearing personal protective equipment or disposing of soiled gloves, administering vaccines has a long-term protective effect that extends beyond the healthcare setting and into the patient's general life. For instance, childhood immunizations protect against diseases such as measles, mumps, rubella, and polio, whereas wearing personal protective equipment, such as gloves and face masks, primarily protects the healthcare worker from infection and controls the spread in a healthcare environment.