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Luca Keller
by on November 6, 2019
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What is shingles?

Shingles occur due to a reactivation of the varicella-zoster virus that lies dormant in the nerve roots of the skin after causing varicella (varicella) of the childhood disease decades earlier.

Shingles generally occurs as a painful rash with blisters in a band of skin provided by a single nerve (dermatome) on one side of the body. Pain often precedes the rash by a few days; sometimes causing it to be mistaken for other conditions.

The pain at the site of herpes zoster eruption that persists for months or years is the most common debilitating result of shingles. Known as post-herpetic neuralgia (PHN), this pain can be continuous, excruciating or triggered by a light touch, such as clothes or a light breeze.

There is no cure for PHN and it is difficult to alleviate more than half of those affected, despite the use of multiple and complex painkillers. Although shingles is treated in advance with antiviral drugs and painkillers, PHN can occur.

Another common complication is ophthalmic herpes zoster, which affects the skin around the eye and can threaten the sight of the person.


How common are shingles?

Almost all Australian adults (over 95%) have been infected with the varicella-zoster virus (although they do not remember having had chickenpox) and are therefore at risk of shingles.

Advanced age is the main risk factor for developing shingles. As we age, our cellular immunity needed to suppress the virus in us diminishes.

About one in three people will develop shingles during their life and about 20,000 Australian adults between the ages of 70 and 79 suffer from it each year.

The older you are when you have shingles the more likely you are to develop complications. PHN occurs after shingles in about one in ten cases in those between the ages of 50 and 59, but rises to one in five in those in their 70s.

People who have a medical condition or treatment (such as cancer) that weakens the immune system are at greater risk of developing shingles, regardless of their age.


The herpes zoster vaccine

The vaccine against herpes zoster or zoster (Zostavax brand) is composed of a living but weakened form of the varicella-zoster virus.

The vaccine is about 14 times more potent than the same vaccine virus in the existing varicella (varicella) vaccines recommended for children, since more viruses are needed to stimulate T cells in the elderly who are already infected.

According to stiaustralia.org, the single-dose zoster vaccine has been registered in Australia and other countries for almost a decade, but with limited availability. It has been shown to be effective and safe for 50 years.

About half of vaccinated people develop pain, swelling or redness at the injection site, but it is usually mild and short-lived.

It is important to note that since it is a live attenuated vaccine, it should not be used in people with a significantly compromised immune system.

How effective is the vaccine and for how long?

The Shingles Prevention Study (SPS) enrolled about 40,000 adults and found that Zostavax, compared to placebo, reduced the risk of shingles by about half (51%) and PHN by about two-thirds (67%) in people aged 60 or over.

But protection against herpes zoster vaccines decreases with age: from 64% in people aged 60 to 69, to 41% between 70-79 years and to 18% for people of equal age or over 80 years.

On the other hand, protection against PHN in individuals between the ages of 70 and 79 was the same as in people aged 60; the risk of PHN was reduced by about two thirds in each group. This means that even if a vaccinated 70-year-old person develops shingles, his chance of getting PHN should be reduced by about 50%.

How long a single dose of the vaccine is still being studied. Clinical studies have shown that protection has decreased over five years after vaccination; the protection can extend longer, but this is uncertain.

At this stage, a second or "booster dose" is not routinely recommended.


Why is the free vaccine offered only to 70-year-olds?

Taking all these considerations into account, the choice of who to provide the free vaccination involved complex modeling that took into account both the peak age of the disease and the severity, and the loss of vaccine effects over time.

After considering these and other factors, the 70-year vaccination - with a "recovery" program that offers free vaccines to children aged 71 to 79 over the next five years - is the most cost-effective strategy.

Outside the funded program, the zoster vaccine can also be prescribed to anyone aged 50 to 69 or over 80, but recipients will have to pay.



Topics: health, herpes, australia
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