Shingles, or herpes zoster, is a painful skin rash caused by the varicella-zoster virus (VZV), the same virus responsible for chickenpox. After chickenpox, VZV remains dormant within nerve cells. If the virus reactivates later in life, it manifests as shingles, typically as a rash with fluid-filled blisters appearing on one side of the body or face.
Shingles Prevalence in Older Adults
The risk of developing shingles significantly increases with age, making it a common concern for older adults. Approximately one in three people in the United States will experience shingles during their lifetime. While anyone who has had chickenpox can develop shingles, it is more common among older individuals, particularly those in their 50s or older.
About half of all shingles cases occur in adults aged 60 or older. The likelihood of the varicella-zoster virus reactivating roughly doubles with each passing decade after age 50, with some estimates suggesting up to half of individuals who live to be 80 may experience shingles. Over 90% of adults over 50 already carry the dormant virus, making them susceptible to the condition.
Understanding the Risk Factors
The increased prevalence of shingles in older adults is primarily linked to the natural weakening of the immune system that occurs with aging, a process termed immunosenescence. After a chickenpox infection, the varicella-zoster virus remains inactive within nerve cells for many years. A robust immune system typically keeps this dormant virus in check, preventing its reactivation.
As individuals age, their immune system’s ability to control dormant viruses, including VZV, gradually declines. This reduction in virus-specific cell-mediated immunity allows the virus to reactivate and travel along nerve pathways, leading to the painful shingles rash. Other factors that compromise the immune system, such as certain medical conditions like HIV/AIDS or cancer, and immunosuppressant medications, can also elevate an individual’s risk of developing shingles, regardless of age.
Preventing Shingles
Vaccination is the most effective method for preventing shingles and its potential complications. The recombinant zoster vaccine, Shingrix, is recommended for adults aged 50 and older. This vaccine is administered as a two-dose series, with the second dose typically given between two and six months after the first for protection.
Health authorities also recommend Shingrix for adults aged 19 and older with weakened immune systems due to disease or therapy. Clinical trials show Shingrix is highly effective, with over 90% efficacy in preventing shingles in adults aged 50 and older. It is 97% effective in adults aged 50 to 69 and 91% effective in those aged 70 and older, protecting against both the rash and the long-term nerve pain known as postherpetic neuralgia. This protection can last for many years, with studies indicating high effectiveness even seven to eleven years post-vaccination. The vaccine is recommended even for individuals who have previously had shingles or received an older shingles vaccine.