What happens after chickenpox
After you recover from chickenpox, the virus does not leave your body completely. Instead, it stays dormant in nerve cells near your spinal cord and brain. This virus can remain inactive for decades without causing any symptoms or problems.
How shingles develops
Shingles occurs when the dormant varicella-zoster virus reactivates. The virus wakes up and travels along the nerve fibers to the skin, causing a painful rash. Scientists do not fully understand why the virus reactivates, but it is more likely to happen when the immune system is weak or when a person is older.
Risk factors for reactivation
Several factors can increase the chance of developing shingles. These include being 50 years or older, having a weakened immune system from illness or medicine, experiencing physical or emotional stress, and having an injury to the area where the rash appears. People with HIV, cancer, or those taking immunosuppressive drugs are at higher risk.
Symptoms and appearance
Shingles usually starts with pain, burning, or tingling in one area of the body, often on one side of the chest or face. After a few days, a red rash appears with fluid-filled blisters that are extremely painful. The rash typically follows the path of a single nerve and stays in one band-like area of the body.
Transmission and contagiousness
A person with shingles cannot give shingles to another person. However, the fluid in the blisters contains the varicella-zoster virus and can spread chickenpox to people who have never had chickenpox or the chickenpox vaccine. This is why people with shingles should cover their rash and avoid contact with high-risk individuals.
Prevention and treatment
A vaccine called Shingrix is recommended for people 50 years and older to prevent shingles. If shingles does develop, antiviral medicines work best when started within 72 hours of the rash appearing. These medicines can reduce pain, speed up healing, and lower the risk of complications. 
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