A person who has a weakened immune system may not be able to fight against infection because

A person with an immune system which is weakened may not be able to fight against infection reason being that the white blood cells which makes up the immune system, fighting off infection and protecting the body against disease which cause organisms are weak.

For a person to be able to fight disease the immune system should be highly complex. For health maintenance thee should be balanced and strong immune system.

Impaired immune response can pose to a serious bad health.

To avoid the influence of immune someone should avoid emotional stress, environmental and chemical exposure and physical stressors for example lack of enough sleep.