Some indications that you may have a weaker immune system than the average healthy person include suffering from chronic sinusitis, developing bacterial sinusitis more than three times in one year, developing pneumonia more than 2 times in one year, and suffering from more than 4 ear infections in one year. Other signs you may have a weakened immune system include regularly feeling fatigued even if you are getting enough sleep every night, it always feels as if you are suffering from a cold, you regularly experienced stomach aches or other digestive issues, and your wounds take longer to heal than what is considered a normal and healthy timeline. Weakened immune systems can also be tested by a health care professional through a blood test to see if the levels of immunoglobins (proteins that fight infections) in your blood is considered normal.