Adult vaccination and priority groups

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The primary infection with the virus that causes herpes zoster results in the disease known as chickenpox (varicella). The virus, varicella-zoster virus (VZV), belongs to the herpesvirus family and is closely related to herpes simplex virus (HSV). Like other herpesviruses, VZV remains in the body for life after the initial infection, persisting in a dormant state within sensory nerve ganglia, where it is normally kept under control by the immune system.

Herpes zoster (shingles) develops when the immune system is no longer able to suppress reactivation of the virus. The characteristic rash usually appears in the area supplied by a single sensory nerve (a dermatome). Some individuals experience recurrent episodes of herpes zoster, and recurrent rashes often occur in the same area of the skin.

The risk of developing herpes zoster increases when immune function is compromised. This may occur with advancing age, during treatment with immunosuppressive medications, or as a result of diseases affecting the bone marrow or other components of the immune system.

In addition to pain and discomfort associated with the rash, secondary bacterial skin infections are the most common acute complication of herpes zoster. Persistent pain and hypersensitivity of the affected skin may continue after the rash has resolved, a condition known as postherpetic neuralgia (PHN). Approximately 10–20% of patients develop PHN following herpes zoster. When herpes zoster affects the ophthalmic branch of the trigeminal nerve, it may involve the eye and can lead to permanent vision loss if left untreated.

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Vaccination against herpes zoster reduces the risk of developing shingles and thereby decreases the risk of acute complications, including vision loss associated with herpes zoster ophthalmicus. It also lowers the risk of persistent pain, even if herpes zoster develops despite vaccination.

In recent years, additional benefits of herpes zoster vaccination have been reported, some of which do not appear to be directly related to the varicella-zoster virus itself. As has been observed with several other vaccines administered to adults, herpes zoster vaccination appears to be associated with a reduced incidence of acute myocardial infarction and stroke.

Both the live attenuated vaccine formerly available (Zostavax®), which is no longer marketed, and the currently available recombinant vaccine, Shingrix®, have been associated with a lower incidence of dementia. Vaccination has also been linked to a slower rate of functional decline in individuals with dementia, including Alzheimer's disease.

Further research is underway to better understand the biological effects of herpes zoster vaccination in older adults and to clarify the mechanisms underlying these observed benefits.

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One vaccine against herpes zoster is currently available in Iceland: Shingrix®. Shingrix is administered as a two-dose series. The second dose may be given as early as two months after the first dose; however, an interval of approximately six months is generally preferred. If vaccine shortages or other circumstances delay the second dose, the first dose should never be repeated. A longer interval between doses is rarely problematic, whereas an interval that is too short may reduce the booster effect of the second dose.

Booster vaccination is not recommended following completion of the two-dose Shingrix series. Individuals who previously received the older live attenuated herpes zoster vaccine (Zostavax®, no longer marketed) may also be vaccinated with Shingrix using the standard two-dose schedule.

Shingrix may be administered to:

• Immunocompromised adults aged 18 years and older, including recipients of solid organ transplants. For individuals receiving cyclical immunosuppressive therapy, vaccination should be scheduled in consultation with the treating physician.

  • If the individual has previously had herpes zoster:

    • If the episode involved the head, vaccination should be deferred until 12 months after the episode.

    • If the episode occurred elsewhere on the body, vaccination may begin

      3 months after the episode, provided all symptoms have resolved.

• Immunocompetent adults aged 18 years and older who have previously had herpes zoster

  • Vaccination may be initiated 12 months after the onset of the rash or other skin symptoms, even if pain persists.

• Adults aged 50 years and older who have not previously had herpes zoster. The vaccine remains highly effective even after the age of 70. However, delaying vaccination increases the likelihood of developing herpes zoster before vaccination. The Chief Epidemiologist of Iceland recommends that individuals who have the opportunity to be vaccinated receive herpes zoster vaccination between 60 and 65 years of age.

Shingrix must not be administered to individuals with a known severe allergy to any of its components or to those who have experienced a severe allergic reaction following a previous dose of Shingrix (see the package leaflet).

- July 2026

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The most common adverse effects following Shingrix vaccination are local injection-site reactions, such as pain, redness, and swelling. These local reactions may be pronounced because the vaccine contains an adjuvant that enhances the immune response to the varicella-zoster virus. Less commonly, recipients may experience fever, headache, muscle pain, or other signs of a vigorous immune response. Adverse effects generally resolve within approximately three days. Antipyretic or analgesic medications, such as ibuprofen or paracetamol (acetaminophen), may be used at the usual recommended doses to help relieve symptoms.

Individuals who choose to receive herpes zoster vaccination are responsible for the cost of the vaccine. Since 1 June 2026, Shingrix has been a registered medicinal product in Iceland. As a result, its price has decreased compared with when it was available only through a special exemption programme, and a more stable supply is expected, as availability had previously been intermittent.