How You Get Shingles
You develop shingles when the varicella zoster virus (VZV) that has been dormant in your nerve cells reactivates, typically when your immune system weakens with age or disease. 1
The Mechanism of Shingles Development
Shingles is not a new infection you "catch" from someone else. Here's the sequential process:
Initial Infection Phase
- You must first have had chickenpox (varicella) at some point in your life, usually during childhood 1
- After chickenpox resolves, VZV doesn't leave your body—it remains dormant in the dorsal root ganglia or sensory ganglia of cranial nerves 1
- Over 90% of the global population has been infected with VZV, making them susceptible to future shingles 2
Reactivation Phase
Shingles occurs when your cellular immune response fails to control the latent VZV replication 1. The virus travels down the nerve to the skin, causing the characteristic painful rash and blisters 3.
Key Risk Factors That Trigger Reactivation
Age-Related Risk
- Your lifetime risk of developing shingles is 20-30% 1
- Risk increases dramatically with age—approximately 50% of people aged 85 years and older will develop shingles 1
- Age-associated immune dysfunction is the primary trigger 2
Medical Conditions That Increase Risk
The following conditions significantly elevate your risk by compromising cellular immunity 1:
- Diabetes mellitus (RR 1.52)
- Cancer/lymphoma/leukemia (RR 1.91)
- HIV/AIDS (RR 1.53)
- Systemic lupus erythematosus (RR 2.08)
- Rheumatoid arthritis (RR 1.51)
- Inflammatory bowel disease
- Cardiovascular and renal disease
- COVID-19 infection (adjusted IRR 1.15) 1
Immunosuppressive Therapy
Patients receiving immunosuppressive medications are 20 to 100 times more likely to develop shingles 4. This includes those on chemotherapy, transplant medications, or chronic corticosteroids.
Important Clinical Caveat
Even if you received the varicella (chickenpox) vaccine, you remain at risk for shingles 1. The vaccine prevents chickenpox but the attenuated virus can still establish latency in nerve ganglia, though the risk may be lower than with natural infection.
Prevention
The most effective strategy to prevent shingles is vaccination with the recombinant zoster vaccine (Shingrix), recommended for adults 50 years and older, or adults 18 years and older who are immunocompromised 1, 5.