ARTICLE IN BRIEF
A new study suggests that the herpes zoster vaccine might be somewhat more effective than originally thought and provide protection for a broader range of elderly persons.
Adults aged 60 or older who received the herpes zoster vaccine were 55 percent less likely to develop shingles than unvaccinated people, according to a new study that might rev up interest in the underused vaccine.
Patients have been slow to get the herpes zoster vaccine since its introduction in 2006. In the latest published government survey, only about 10 percent of adults aged 60 or older had received the vaccine.
The new study, reported in the Jan. 12 edition of the Journal of the American Medical Association, suggests that the vaccine might be somewhat more effective than originally thought and provide protection for a broader range of elderly persons.
“The vaccine is associated with a 55 percent reduced risk for shingles, and the reduced risk is consistent across sex, age or racial groups in patients with chronic diseases,” Hung Fu Tseng, PhD, MPH, the study's lead author and research scientist at Kaiser Permanente Department of Research and Education, told Neurology Today. “In terms of adult vaccines, this is a significant reduction.”
The investigators compared the medical records of 75,761 members of Kaiser Permanente, Southern California, aged 60 or older who received the vaccine between January 2007 and December 2009, with those of 227,283 members who were not vaccinated.
The follow-up period averaged 1.56 years for the vaccinated group and 1.72 years for the unvaccinated group. Among those who were vaccinated, there were 6.4 cases of herpes zoster per 1,000 person-years, versus 13 cases per 1,000 person-years among the unvaccinated group.
The study excluded immunocompromised patients but included those with a variety of medical conditions, including diabetes, and heart and lung disease. The study's endpoints were incidence of herpes zoster and incidence of ophthalmic herpes zoster, as well as hospitalization related to shingles. The study did not measure the incidence of postherpetic neuralgia.
The benefit of the vaccine extended to all types of patients. “The reduction in risk did not vary by age at vaccination, sex, race or with presence of chronic diseases,” the researchers reported. In addition to the 55 percent reduction in the risk of shingles, the vaccine lowered the risk of ophthalmic herpes zoster by 63 percent and the risk of hospitalization related to shingles by 65 percent.
“Our data complement the results of the original clinical trial of herpes zoster vaccine [reported in 2005 in The New England Journal of Medicine], indicating that the vaccine was associated with a reduced risk of herpes zoster in a community setting with its mixed population and routine clinical practices,” the researchers wrote.
In the study that led to the vaccine's approval for marketing, the vaccine was shown to reduce the risk of shingles by 51 percent and the risk of postherpetic neuralgia by 67 percent. Kenneth L. Tyler, MD, the Reuler-Lewin Family Professor and Chair of Neurology at the University of Colorado-Denver, said that while the new paper was basically a confirmatory study,” it was carried out in “closer to a real-world setting.”
“The results are almost identical to the original study, but this study adds some important nuances,” Dr. Tyler told Neurology Today, for which he is an associate editor.
Richard B. Tenser, MD, professor of neurology and microbiology and immunology at Penn State University College of Medicine, said the new study was notable because “it looked at people with lots of other illnesses and it worked in all those groups.”
“It should boost people's confidence that the vaccine really does work,” Dr. Tenser told Neurology Today.
The federal Centers for Disease Control and Prevention (CDC) recommends the herpes zoster vaccine for everyone 60 or older, with the exception of patients who are immunocompromised or fall into one of a few other categories. A CDC survey from 2009 found that only about 10 percent of older adults received the vaccine, up slightly from 6.7 percent the year before. By comparison, about two-thirds of adults 65 or older received the annual flu shot and 60 percent, the pneumococcal vaccine.
WHY THE VACCINE IS UNDERUSED
Researchers cite a number of reasons for why the shingles vaccine has been slow to catch on. “I think there are patients and doctors who think shingles is not so bad, that it's just a mild illness, so they're not going to go to any length to prevent it,” Dr. Tenser said.
Previous studies have questioned its cost-effectiveness, and cost is also an issue. According to an article in the May 4, 2010, edition of the Annals of Internal Medicine, “the herpes zoster vaccine is the most expensive vaccine recommended for older adults.” Dr. Tseng estimated the shot costs about $200 and said that it may not be paid for by a patient's insurance. The vaccine is covered under Medicare Part D, not Part B, and a patient's out-of-pocket costs for the vaccine will vary, according to the CDC.
Other potential reasons for slow uptake is that despite the 55 percent relative risk reduction, the absolute reduction is only from 1.3- to .64 percent (less than 1.0 percent over one to two years.
Giving out the shot might also be a hassle for doctors. The shingles vaccine requires careful handling because it has to be kept frozen. Pediatric practices tend to have better systems than adult practices to administer vaccines.
Dr. Tyler said many patients may not be aware of just how severe the complications of shingles can be. “About 40- to 50-percent of patients over the age of 60 who get shingles, for instance develop postherpetic neuralgia,” he said. “It can be terribly disabling and involve excruciating pain,” perhaps lasting for months or even years.
VACCINE WORKS AGAINST GROUPS
According to background information in this latest study, there are about 1 million cases of shingles annually in the US. The researchers noted that while the seminal study that led to the vaccine's approval showed that it “works under idealized conditions,” additional research was needed to see whether “benefits of the vaccine can be generalized to conditions of clinical practice.”
“This is particularly important for herpes zoster vaccine, given the medical and physiological diversity in the elderly population for whom the vaccine is indicated and since there are stringent storage and handling requirements for this live-attenuated vaccine,” the researchers wrote. “Moreover, a large observational study also allows for exploration of vaccine benefits among important patient subgroups that would be unfeasible in most randomized controlled trials.”
The researchers said that one case of shingles could be prevented for every 71 people vaccinated. Dr. Tseng said the finding that the vaccine was effective for the older elderly in the study was particularly interesting because the clinical trial data suggested the vaccine might not work as well for that older age group. He said it was also noteworthy that the vaccine offered protection for patients with a variety of medical conditions.
“There was a concern that if patients are taking medicine for other conditions that it might interfere with the performance of the vaccine or interfere with their immune response to the vaccine,” he said. But that didn't seem to be the case.
“Our results support recommendations to offer herpes zoster vaccine to eligible patients of all ages including the oldest population,” the researchers wrote. “Not only might these patients experience a reduction in their relative risk of herpes zoster, but for the oldest group, this could translate into a very large reduction in disease burden because they bear the greatest burden of herpes zoster and postherpetic neuralgia and are also especially vulnerable to these disabling conditions.”
Dr. Tenser said neurologists and other practitioners who care for older adults need to encourage their patients to get vaccinated. ”Shingles primarily affects older people and the US population is aging,” he said. “We are going to see more and more shingles.”