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.
Similarly, some people experience further anxiety as a result of their back pain, regardless of whether the initial back pain was caused by anxiety. Since anxiety can cause back pain because of muscle tension, posture changes, etc., this may also make the back pain worse. While it may not have been initially caused by anxiety, anxiety contributed to the back pain cycle.