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.
The main cause of neck pain is tension. During periods of intense anxiety, your muscles tense up dramatically. Muscle tension tightens the muscles, especially in the shoulders, back, and neck. The more anxiety you experience, the more your tension may cause significant pain and discomfort. A related issue comes from the mindset of those with anxiety. Many people get muscle tension in their neck during times of stress.
Strain to neck muscles, called cervical strain, can be due to muscle spasm following an injury. Whiplash, poor posture, psychological stress that causes you to tense your muscles, poor sleeping habits, and/or sports injuries are common causes of cervical muscle spasm. Symptoms associated with this type of neck disorder can include pain, stiffness, and/or tightness in muscles that lasts up to six weeks.