Shingles, medically known as herpes zoster, is a painful rash caused by the varicella-zoster virus (VZV), the same virus responsible for chickenpox. After recovery, VZV remains in the body in a dormant state. Understanding the nature of the virus and the immune system’s role helps explain why subsequent episodes are possible, which is a common concern for those who have already experienced the condition.
Understanding the Virus and Latency
The varicella-zoster virus establishes a lifelong presence in the body following the initial chickenpox infection. The virus retreats and becomes latent, residing within sensory nerve ganglia near the spinal cord and brain. The body’s immune system, specifically cell-mediated immunity, works constantly to keep the dormant VZV from reactivating.
The first episode of shingles occurs when the immune surveillance keeping the virus suppressed begins to weaken. The VZV then reactivates, travels along the nerve fibers to the skin, and produces the characteristic blistering rash and localized pain. This process of reactivation is driven by a decline in the immune system’s ability to maintain control.
Yes, Shingles Can Recur
While many people consider shingles a one-time event, recurrence is a recognized medical possibility. Studies estimate that a second or third episode of shingles occurs in approximately 1.2% to 9.6% of the general population who have had the virus once. This rate is higher in specific high-risk groups, sometimes reaching up to 18.2% in immunocompromised individuals.
The time between the initial episode and a recurrence can vary significantly, ranging from months to over a decade. The average time is often reported to be around three years between episodes. Recurrence typically happens because the body’s immune response, which was boosted by the first outbreak, wanes over time, allowing the virus to reactivate again.
Recurrent episodes may be milder than the initial case, but this is not universally true, as severity depends heavily on the individual’s current immune status. Repeat outbreaks often occur in a different area of the body than the first time, corresponding to a different nerve pathway.
Conditions That Increase Recurrence Risk
The primary factor driving the risk of shingles recurrence is a weakened or compromised immune system. Age is a significant factor, as the immune system naturally declines after age 50, a phenomenon known as immunosenescence. This age-related weakening makes both the first and subsequent episodes more likely.
Specific health conditions also significantly elevate the risk of repeat episodes. These include chronic diseases that suppress immune function, such as human immunodeficiency virus (HIV)/AIDS, cancer, and autoimmune diseases. Medical treatments can also compromise immunity, including chemotherapy, high-dose corticosteroids, and immunosuppressant drugs used for organ transplants.
Other factors associated with increased recurrence include having an initial episode that resulted in long-lasting pain (zoster-related pain) for more than 30 days. Chronic conditions like diabetes, chronic kidney disease, and hypertension have also been identified as contributing risk factors.
Preventing Future Episodes
For adults, the most effective step for preventing future episodes is vaccination. The recombinant zoster vaccine (RZV), Shingrix, is recommended for healthy adults aged 50 years and older, regardless of whether they have had shingles before. This vaccine provides strong protection against both shingles and its most common complication, postherpetic neuralgia.
The vaccine is administered in two doses given two to six months apart. The Centers for Disease Control and Prevention (CDC) also recommends the vaccine for adults aged 19 and older who are or will be immunocompromised due to disease or therapy. Even after a shingles episode, vaccination is recommended because the natural immunity gained from the infection often wanes over time.
If a recurrence does happen, prompt treatment with antiviral medications, such as acyclovir or valacyclovir, is important. Starting these medications within 72 hours of the rash’s onset can shorten the duration of the illness and reduce the risk of long-term nerve pain. Beyond medical interventions, maintaining a healthy lifestyle through adequate sleep, managing stress, and good nutrition supports overall immune function against VZV reactivation.