The immune system is a complex network of cells, tissues, and organs that work together to protect the body from harmful invaders such as bacteria, viruses, and parasites. However, there are times when the immune system may not function properly, leading to various weaknesses.

One of the common weaknesses of immunodeficiency disorders, which can be caused by genetic mutations or acquired diseases such as HIV/AIDS. Another weakness is autoimmune diseases, in which the immune system attacks healthy body cells instead of foreign invaders.

In addition, chronic stress, improper nutrition, lack of sleep and certain medications can also weaken the immune system's ability to fight infections. It's important to maintain a healthy lifestyle and seek medical attention if you suspect your immune system is compromised.

Source :

https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentID=123&ContentTypeID=134#:~:text=Your%20immune%20system%20can%20also,most%20people%20can%20fight%20off.