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.
The most common causes of low back pain are: 1  Injury or overuse. 2  Pressure on nerve roots from conditions such as a herniated disc or spinal stenosis. 3  OsteoarthritisOsteoarthritis, which is usually caused by getting older.