VACCINE RESOURCE COMMITTEE

of the Edmonton Zone Medical Staff Association

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Herpes zoster (shingles) Vaccine Question #1:

What is shingles?

Once a person has chickenpox, they will always have the virus in their body. Sometimes the virus becomes active again, causing shingles followed by postherpetic neuralgia.

Herpes zoster (shingles) is a manifestation of reactivation of the varicella-zoster virus (VZV), a DNA virus of the Herpesvirus family, which, as a primary infection, causes varicella (chickenpox). Treatment options for HZ and PHN have limited effectiveness.

Any person who has had varicella is at risk of developing HZ. However, HZ occurs most frequently among older adults and immunocompromised persons. Age is the most important risk factor for development of HZ. Over two-thirds of the cases occur in individuals over 50 years of age. This age-related risk may be explained by both waning immunity over time following the initial varicella infection, and the loss of components of VZV-specific cell mediated immunity as a result of natural aging processes. The severity of illness associated with HZ and its complications also increases markedly with age. Up to 10% of persons over 65 years of age will be admitted to hospital with an episode of HZ.

VZV causes two distinct clinical syndromes: primary infection (varicella, also called chickenpox) and reactivation of latent infection (HZ, also called shingles). Following varicella, VZV establishes latency in the sensory nerve ganglia, and may reactivate later as HZ. HZ infection is characterized by pain and a unilateral vesicular eruption, usually in a single dermatome. Complications of acute HZ are potentially severe. The risk of mortality from VZV-associated disease is low.

The most frequent complication of acute HZ is PHN which is characterized by prolonged and often debilitating neurogenic pain that lasts for more than 90 days from the onset of rash. Because treatment options for PHN are of limited effectiveness, PHN often has major adverse impacts on quality of life. Older adults, people living with chronic conditions such as diabetes or autoimmune diseases, and persons who are immunocompromised may be at greater risk of developing PHN. They are also at risk of experiencing longer lasting HZ rash than the general population. Other potential complications of HZ include ophthalmic sequelae (herpes zoster ophthalmicus), central nervous system infection, nerve palsies including the Ramsay-Hunt Syndrome, neuromuscular disease including Guillain-Barré Syndrome, pneumonia, hepatitis and secondary bacterial infections.

sources:

Government of Canada: Herpes zoster (shingles) vaccine: Canadian Immunization Guide
Cleveland Clinic: Postherpetic Neuralgia