Shingles is caused by the reactivation of the inactive chickenpox virus (varicella zoster virus), which infects 99% of adults 50 years of age and older in the United States.
Your immune system naturally weakens as you age, so your risk for shingles increases as you get older — even if you feel healthy. Almost one in three people in the United States will develop shingles in their lifetime, leading to about one million cases of shingles per year. The shingles vaccines can offer protection against shingles. The U.S. Centers for Disease Control and Prevention recommends all adults with healthy immune systems age 50 years or older get vaccinated.
No, shingles is not contagious and it cannot be passed from one person to another. It can, however, cause chickenpox in someone who has never had chickenpox or the chickenpox vaccine (if they come in contact with the fluid of a shingles blister). Once the shingles blisters have developed crusts, they are no longer contagious.