What type of agent is described as preventive and serves to prevent disease?

The term that accurately describes an agent designed to prevent disease is prophylactic. Prophylactic agents are used to ward off diseases before they can occur, often through means such as vaccinations or medications taken to prevent the onset of specific health issues. In public health, prophylactics play a crucial role in controlling the spread of infectious diseases and in safeguarding individuals at risk of developing certain health conditions.

Other types of agents, such as therapeutic agents, are aimed at treating diseases after they have manifested, focusing on alleviating symptoms or curing conditions. Diagnostic agents help in identifying diseases rather than preventing them. Curative agents work to eliminate a disease that has already developed. Thus, the role of prophylactics is distinctly preventive, emphasizing their importance in maintaining health and preventing illness.