Compiled by Dr Allison Glass, Clinical Virologist, Lancet Laboratories

Herpes zoster, commonly known as shingles, is caused by the Varicella-Zoster virus (VZV). Following a primary infection, VZ Venters the body via the respiratory tract, spreads via the blood to the skin, and typically results in chickenpox. This primary infection leads to lifelong immunity that almost always prevents further episodes of chickenpox due to repeat infections.

As the immune system clears the primary infection, VZV is able to establish a latent infection in nerve roots. Latent virus does not replicate and thus does not continue to stimulate an immune response. Good cellular immunity (mediated by the T-lymphocytes) is important for maintaining this viral latency. If cellular immunity is impaired, however, VZV is able to become active again.

When VZV is reactivated, it travels down sensory nerves to infect epithelial cells. This may result in shingles, a skin rash that affects the skin supplied by the specific sensory nerves involved. For this reason, the rash is dermatomal and does not cross the midline. The thoracic, trigeminal, lumbar and cervical dermatomes are the most frequent sites involved.

The rash by may be preceded by tingling or pain over the affected area for a few days before the onset of the rash. The rash begins as macules and papules, before evolving to vesicles, pustules and ulcerations. The rash crusts over a period of 7-10 days.

The most important complication of shingles is post-herpetic neuralgia (PHN).This is chronic nerve pain over the affected site that persists for at least 3months after the rash resolves. The pain may however last indefinitely and can severely impact on quality of life. PHN is more common if shingles occurs after the age of 50 years.

Other complications include:

  • Scarring
  • Organ involvement
  • Eye involvement with resulting loss of vision (if trigeminal nerve involved)
  • Meningo-encephalitis
  • An increased risk of stroke for 6-12 months following the episode of shingles

Approximately 90{c7b83ef3f28a5a4d1b92af1005aa96857b6821a19c5bf7bda4f75f8b16806b7f} of the adult population have been infected with VZV and are thus at risk for the development of shingles. It is estimated that one in four adults will develop shingles in their lifetime. Risk factors that increase the likelihood of developing shingles include:

  • Advancing age – this is the most important risk factor with 60{c7b83ef3f28a5a4d1b92af1005aa96857b6821a19c5bf7bda4f75f8b16806b7f} of cases occurring after the age of 50 years.
  • Immunosuppression including HIV infection, malignancies, organ transplantation, SLE, immunosuppressive therapy and diabetes.
  • Physiological trauma
  • Psychological stress

If shingles is suspected, it should be treated as soon as possible with acyclovir/valacyclovir and adequate pain management. This reduces the duration of the episode and the risk of developing complications including PHN.

A vaccine is available for the prevention of shingles and PHN. It is licensed for use in individuals over the age of 50 years. The vaccine boosts VZV-specific cell-mediated immunity.

The Shingles Prevention Study, which included 40000 people over the age of 60 years, found that the vaccine reduced the incidence of shingles by 51.3{c7b83ef3f28a5a4d1b92af1005aa96857b6821a19c5bf7bda4f75f8b16806b7f}, the burden of illness from shingles by 61.1{c7b83ef3f28a5a4d1b92af1005aa96857b6821a19c5bf7bda4f75f8b16806b7f} and PHN by 66.5{c7b83ef3f28a5a4d1b92af1005aa96857b6821a19c5bf7bda4f75f8b16806b7f}. A subsequent study demonstrated that vaccination of individuals 50-59 years of age resulted in vaccine efficacy for the prevention of shingles of 69.8{c7b83ef3f28a5a4d1b92af1005aa96857b6821a19c5bf7bda4f75f8b16806b7f}. In both studies the vaccine was well tolerated.

The vaccine contains live attenuated virus. For this reason it is contraindicated in individuals with primary or acquired immune deficiencies. Further contraindications include:

  • A history of anaphylaxis to gelatin, neomycin or any other component of the vaccine.
  • Persons on immunosuppressive therapy including high-dose cortisone therapy.

The vaccine is not indicated for the prevention of chickenpox as the dose of virus in the zoster vaccine is significantly higher than that in the varicella vaccine. It is, however, not considered necessary to test an adult over the age of 50 years for past exposure to VZV prior to administering the zoster vaccine.

The most commonly reported adverse events following vaccination include pain and redness at the vaccination site, and headache. There have been reports of asthma exacerbation, congestive heart failure and the development of polymyalgia rheumatic following vaccination, but these are rare.

The vaccine should be stored frozen until reconstituted. It may be refrigerated for no more than 72 hours prior to reconstitution. Once reconstituted, it should be administered within 30minutes. The vaccine must be given subcutaneously. It should not be administered at the same time as the pneumococcal vaccine as this may result in a poorer response to the vaccine. It may be administered at the same time as the influenza vaccine.

A booster dose of the vaccine is probably indicated 8-10 years after the initial dose.

This article is an extract from the IPA news online magazine and can be accessed here:


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