Answer:
1. Weak Immune system - If your immune system in general is weak then is it very common or very likely for you to often become sick and ill and/or carry the presence of an infection in your body because there may be certain things that your body is not used to so those factors could lead to an infection.
2. Advanced age - When you are young or when you are old, your body and the immune system is very, very fragile and weak. Anything and everything could possibly make you sick and cause an infection or disease in your body. This is more likely for elderly people and young infants because, for elderly people, their immune system has gone weak and for infants, it's because their immune system is not yet built and not strong enough.
3. Malnutrition - Malnutrition means your diet is missing various important dietary required nutrients. So it's a lack of certain nutrients and this could potentially put an individual at risk of infection because it all ties up to your immune system becoming weak. Your immune needs all the proper amounts of all the important nutrients and if it is deficient of one nutrient that imbalances your immune system and could lead to one part of your immune system being very weak and prone to an infection or disease while the other part is very strong and is not prone to infections or diseases.
4. Bacterial resistance or antibiotic resistance - This usually occurs when there is the presence of more than one prescription medication or antibiotic because the bacteria in your body becomes resistant to some of the strongest antibiotics and medications available so therefore the bacteria remains in your body and the longer the bacteria stays the more dangerous it gets and the more it affects your body leading to severe infections and possibly to death.
5. Cognitive deficits - This is the term used to describe impairment in an individual's mental processes that lead to the acquisition of information and knowledge, and drive how an individual understands and acts in the world. The following areas constitute domains of cognitive functioning: attention and decision making. This could put an individual at risk of infection especially in their brain because of their impairment. Which means they cannot think or function or react the same way to situations in which most people do.
These are 5 factors that I think could put an individual at risk of infection. I hope these are the answers you're looking for and hopefully, my explanations were helpful. Sorry if it is a lot to process but I tried to my best ability to answer in the easiest way possible. Apologies, for the big load of writing.