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Tuesday, June 17, 2014

Effects of chickenpox vaccine on development of shingles yet to be seen

As published in the Washington Observer-Reporter

As though chickenpox isn't enough of a scourge on its own, the virus (varicella-zoster virus) that causes the itchy blisters also gifts humanity with pox's daughter, shingles.

Commercials, brought to Americans by trusty pharmaceutical companies, have taught that one must have had chicken pox in order to be at risk for shingles later in life. The virus that causes both illnesses takes up residence inside nerves until a chance to reemerge later, such as times of increased stress, trauma or immune system compromise.

While this is true, the effect of the chickenpox vaccine, which was first recommended for routine use in 1995, on the incidence of shingles is a slightly more complicated topic. These individuals' immune systems never actually fight the virus but are exposed to it just enough to develop antibodies capable of preventing an actual infection in the future. But, is this low-grade exposure to the varicella-zoster virus enough to cause shingles?

An informal poll of physicians yielded conflicting answers to this question, with many siting the "promise" of shingles prevention as a part of the presumed value of the chickenpox vaccine when it was first promoted.

On the other hand, a recent study discusses a six-fold increase of shingles across all age groups, including children.

The answer seems to lay in the somewhat unpredictable behavior of live attenuated (or weakened) vaccines.

"Since the (chickenpox) vaccine is a live virus, it's possible that the attenuated virus lives in your nerves just like the real varicella-zoster virus," said Dr. Marc Yester, a pediatrician at Peters Township's Pediatrics South. "That makes it possible to reactivate like the real virus; although, it would be a lot less likely to, and, if it did, it should be a much, much milder version."

The "would" and "should" are the result of timing.

"We're just now seeing how the varicella vaccine works as kids grow up," said Dr. Yester, noting that those first vaccinated are around only 20 years old.

A complete answer to the question may not come for quite some time as the number one risk factor for shingles is increasing age. It is estimated that 50-percent of those living to age 85 will have an episode of shingles with 32-percent of Americans expected to have an episode during their lifetimes.

Varicella-zoster virus may cause both chickenpox and shingles, but their rashes have personalities all their own differing in both distribution on the body and pain.

"The location (of shingles) is going to follow one nerve and show up only in the area the the nerve covers," said Dr. Yester. "But, the standout feature is the pain; Very few rashes come with this kind of pain."

Pain that is preventable up to 50-percent of the time by the shingles vaccine, available to those 50 years old or older. Not only does the vaccine prevent these unpleasant episodes, but they also work to decrease the incidence of the chicken pox since shingles, too, is contagious with direct contact--an improvement upon the chickenpox which is also communicated when the individual coughs or sneezes, sending the virus into the air.

While society and scientists wait to witness the effects of the chickenpox vaccine on developing shingles, we can speak in terms of odds.

"It does not surprise me that people can get shingles even if they've been vaccinated," said Dr. Yester. "The vaccine doesn't put up a force-field around us, but having the vaccine should lower the risk."

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