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.
How Does Stress Cause Neck and Shoulder Pain? Holding the shoulders in this raised position causes the neck and shoulder muscles to become shortened and tight. The muscles become strained particularly at the tendons where they join the area of bone at the back of the skull called the occiput.