Active and Passive Immunity. Naturally acquired active immunity occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response. Artificially acquired active immunity can be induced by a vaccine, a substance that contains the antigen.
Lower back tightness can cause muscle twitching, pain and reduced range of motion. Lower back muscle tightness is the cause of a muscle spasm. This can be brought on by a strain, overuse or muscle weakness, according to BetterMedicine.com.
Common Causes of Back Pain. 1  Whether your back pain is chronic or acute, it's possible to find some relief. 2  Weight. 3  Overweight people have an increased risk for back pain.  Sedentary 1  lifestyle. Lack of exercise can cause or worsen back pain because of increased stiffness and weakened muscles.  Sitting posture.