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.
What Causes Back Muscle Pain? Most causes of low back pain are muscle, ligament or joint related. Commonly, these back injuries are caused by muscular strains, ligament sprains and joint dysfunction, particularly when pain arises suddenly during or following physical loading of your spine.