Chickenpox vaccine for grown-ups
In 1995 the pediatric community welcomed a new vaccine from Merck called Varivax, which wards off the highly contagious chickenpox. Based on a vaccination is not for fear they might catch the infection from their grandkids. Rather, it's to prevent shingles, a re-emergence of the very same varicella zoster virus that has been languishing in their bodies since they had their own chickenpox in childhood.
Varicella zoster is a herpes virus, and like others in the herpes family, once caught it last forever. After childhood chickenpox recedes, the virus retreats quietly into sensory nerve roots. For reasons we still don't fully understand but in part because of lagging immunity, the virus, in its reincarnation called herpes zoster, can erupt decades later in a single nerve root. A band of nerve fibers on one side of the body becomes inflamed and swollen and triggers tender, fluid-filled vesicles in the patch of skin that the nerve root enervates. If a cranial nerve is affected, spots can appear on the forehead, involve an eye or ear, or even cause temporary paralysis of one side of the face. When the virus reactivates in a spinal nerve, shingles appear elsewhere in the body (typically on one side of the trunk) along the sensory line that defines the inflamed nerve root. What's most debilitating is the intense if not excruciating pain that can linger at the site for months after the skin eruptions have healed and gone. Fortunately, herpes zoster rarely strikes twice.
Though the adult vaccine does not eliminate the disease, it cuts the numbers in half, and for those who get shingles, post-herpetic nerve pain is reduced by almost 70 percent. What's not known is how long its benefits last. The Food and Drug Administration is now reviewing the vaccine, and if all goes well, its release will be good news for the million or so American adults who come down with shingles each year.
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