What is herpes zoster?

Herpes zoster, also known as shingles, is a viral infection caused by the varicella zoster virus (VZV) — the same virus responsible for chickenpox. After recovering from chickenpox, VZV remains inactive in the body but can reactivate later when the immune system weakens.
 

Symptoms of herpes zoster

Typical symptoms include painful blisters and a skin rash. Additional symptoms may include fever, headache, chills, and upset stomach.
 

Dangers and complications

• Post-herpetic neuralgia (PHN): Severe nerve pain lasting weeks, months, or even years after the rash clears, sometimes significantly affecting daily life.

• Skin infections: Bacterial infections can lead to scarring.

• Eye complications (Herpes zoster ophthalmicus - HZO): May cause eye damage or vision loss.

• Neurological complications: Increased risk of stroke, meningitis, brain tissue necrosis, and facial paralysis.

Transmission of herpes zoster

Herpes zoster is communicable. Blisters contain fluid with the varicella zoster virus, which can spread the infection to others. Individuals over 50 years and those with weakened immune systems have the highest risk.
 

Who should receive the herpes zoster vaccine?

• Adults aged 50 and older: Risk increases with age, even if they never had chickenpox. Those who've had shingles before still face a 6.2% recurrence risk.

• Adults aged 18 and older with weakened immune systems due to illness or therapy.

• Individuals with chronic illnesses such as diabetes, lung, or kidney diseases, or previous COVID-19 infections, due to heightened risk.

Who should consult a healthcare professional before vaccination?

Consultation is essential for:

• People with severely weakened immune systems (unsuitable for live-attenuated vaccines).

• Individuals with a history of severe allergic reactions to vaccine components.

• People currently experiencing herpes zoster.

• Pregnant women.

Types of herpes zoster vaccines available in Thailand

1. Zoster vaccine live (ZVL)

• Recommended for adults 50 years and older.

• Single dose (0.65 mL) administered subcutaneously.

• Efficacy: 69.8% (ages 50-59) to 51% (ages 60+) for preventing shingles, and 66.5% to 39% respectively for preventing PHN.

 
2. Recombinant zoster vaccine (RZV)

• Administered as two intramuscular injections (0.5 mL each).

  • Adults 50+: Second dose given 2 to 6 months after the first. Over 90% effective in preventing shingles and PHN.

  • Adults 18+ with weakened immune systems: Second dose given 1 to 2 months after the first. Efficacy ranges from 68-91%.

• Fully effective 4 weeks after completion of the vaccine series.

• Protection lasts approximately 10 years. Booster dose recommendations are not yet established.

• Individuals previously vaccinated with ZVL should wait at least 2 months before receiving RZV, which requires two doses.

Side effects of herpes zoster vaccines

Common side effects include pain, redness, or swelling at the injection site, tiredness, muscle pain, headache, chills, fever, stomach pain, and nausea.
Timing recommendations for vaccine administration

• Those who've had herpes zoster should wait at least 6 months post-recovery before vaccination.

• Individuals transitioning from live-attenuated to recombinant zoster vaccine should allow a minimum 2-month interval.

 
Prevention
 Maintaining overall health helps prevent shingles, with vaccination being the most effective preventative measure. Always consult a healthcare professional for personalized advice.