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.
Sitting or standing for long periods of time can also cause serious middle back pain. The effects of poor posture on the back may not cause middle back pain immediately. Instead, this causes pain gradually over time.Often as a result of muscle strains and sprains or other minor back injuries, muscle spasms and cramps can be another cause of middle back pain.This condition occurs when muscles in the back tense up.nstead, this causes pain gradually over time. Often as a result of muscle strains and sprains or other minor back injuries, muscle spasms and cramps can be another cause of middle back pain. This condition occurs when muscles in the back tense up.