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.
Back cramps can be painful and debilitating, and can be caused by a number of different things. Injury to the back, such as a pulled muscle, is one of the most common causes of back cramps. Poor posture, overexertion through exercise, improper lifting methods, or even menstrual cramps can all cause back pain as well, however, in addition to issues with the vertebrates of the spine. The most common cause of back cramps is physical injury.