A New Protection for Older Adults: Herpes Zoster Vaccine
December is a good month to think of vaccinations. With the “flu season” upon us, the influenza vaccine should be given to all older individuals, as discussed in the October issue of Clinical Geriatrics.1 Now is also a good time to make sure that all elderly persons have had their vaccination against pneumococcal infection. This year, however, there is a new vaccine to consider. The U.S. Centers for Disease Control and Prevention has recommended that everyone over age 60 years be vaccinated against herpes zoster. Almost all elderly persons, whether they remember it or not, have been exposed at some point in their past to the chicken pox, or varicella virus. Frequently referred to as shingles, herpes zoster infection in the older person is a “reactivation” of the virus that has remained dormant in their dorsal root ganglia adjacent to the spinal cord or the ganglion semilunare (ganglion Gasseri) in the cranial base. With reactivation, the virus starts replicating in the nerve cells, and newly formed viruses are carried down the axons along a dermatome to the area of the skin served by that ganglion. While the blisters that result from this infection most often are found on the trunk of the body, they may also affect the face and even the eyes, potentially leading to blindness.
Disease may be associated with acute pain, but the pain may last months or even years (postherpetic neuralgia). Approximately 50% of persons over the age of 85 years have experienced at least one episode of herpes zoster reactivation. This year, we can offer a vaccine that was approved by the Food and Drug Administration in May 2006. While not all insurance companies have decided to pay for this vaccine, universal acceptance is almost certain in the near future. Herpes zoster infection in the elderly has been linked to an age-related change in immunity, and its occurrence in the elderly has always alerted me to evaluate the person for some underlying illness or occult malignancy. Corticosteroid use and emotional stress are also risk factors. Some have proposed that the number of cases will increase now that there has been a reduction in zoster infection in children due to the almost universal childhood vaccination against varicella virus. In fact, one study in Massachusetts demonstrated a 90% increase in the incidence of herpes zoster from 2.77/1000 to 5.25/1000 cases in a 4-year period of time following the initiation of a varicella vaccination program for children.2
Childhood vaccination has resulted in less exposure of elderly persons to the virus, and thus less of an ability to have an immunological boost from this exposure and protection against reactivation. The new vaccine has proven successful in preventing at least half of the expected cases of herpes zoster in a study of 38,000 people. It also reduced by two-thirds the number of cases of post-herpetic neuralgia in those who were infected.3 Clearly, this is something additional to think about when you see your patients this month or in the future.