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Stronger Chickenpox Vaccine Effective Against
Shingles in Older Adults
Massive study produces dramatic results with cases
cut in half, less severity in others
June 1, 2005 – Half of all people who live to age
85 will get shingles and endure a long period of misery. Today there is
new hope for relief in the announcement of an experimental vaccine that
prevented about half of the cases of shingles and dramatically reduced
its severity and complications for those vaccinated.
Experts estimate more than a million new cases of
shingles occur in the United States each year and the two major risk
factors are increasing age and declining immunity.
In one of the largest adult vaccine clinical trials
ever, researchers have found dramatic results with an experimental
vaccine against shingles - zoster vaccine. The findings appear in the
June 2 issue of The New England Journal of Medicine.
The Shingles Prevention Study, conducted over 5
½-years, was led by the Department of Veterans Affairs (VA) and carried
out in collaboration with the National Institute of Allergy and
Infectious Diseases (NIAID), part of the National Institutes of Health (NIH),
and Merck & Co., Inc. (Whitehouse Station, NJ).
"This is very promising news for older persons,"
says Stephen E. Straus, M.D., an infectious diseases specialist at NIAID
and Director of the NIH National Center for Complementary and
Alternative Medicine, who participated in the design, oversight and
conduct of the trial. "These striking results indicate for the first
time that we can use a vaccine to prevent shingles, one of the most
common and debilitating illnesses of aging. And among vaccine recipients
who did get shingles, the episodes generally were far milder than they
otherwise would have been."
"For some people, shingles can result in months or
even years of misery," comments study leader Michael N. Oxman, M.D., an
infectious disease specialist at the San Diego VA Healthcare System and
the University of California, San Diego.
Shingles, also known as herpes zoster, is caused by reactivation of the
virus that causes chickenpox. Once chickenpox infection has run its
course, the virus is not eliminated; rather, it retreats to clusters of
sensory nerve cells usually located near the spinal cord, where the
virus persists in a dormant state. As immunity weakens with advancing
age, the virus can reactivate, multiply in and damage sensory nerve
cells to cause pain. It then migrates to the skin, causing the
blistering rash of shingles.
Generally, shingles first manifests as pain,
itching or tingling in an area of skin on one side of the body or face.
Then a painful blistering rash develops in that same area of skin; the
rash can take two to four weeks to heal.
Anyone who has had chickenpox--which includes most
adults in the United States--could develop shingles, though not all
will. The two major risk factors are increasing age and declining
immunity. Half of all people who live to age 85 will get the disease.
Experts estimate more than a million new cases of shingles occur in the
United States each year.
The trial was conducted at 22 study sites
nationwide, including 16 VA medical centers and six clinical research
sites outside the VA system coordinated through NIAID.
Between November 1998 and September 2001, the
multicenter research team enrolled more than 38,500 men and women age 60
or older into the study. Half of the participants received a single
injection of the zoster vaccine--a live, weakened form of varicella-zoster
virus, the virus responsible for chickenpox; the other half received a
placebo vaccine.
Neither the researchers nor the participants knew
who received vaccine and who received placebo until after the study was
over. The zoster vaccine used in the study, manufactured by Merck, is a
new, more potent version of the chickenpox vaccine used to prevent
chickenpox in millions of American children every year since 1995. The
zoster vaccine was developed specifically for study in older adults.
During an average of more than three years of
follow-up, the vaccine reduced the incidence of shingles by 51 percent:
642 cases of shingles occurred among those in the placebo group compared
with only 315 in the vaccinated group. Among all vaccine recipients, the
total burden of pain and discomfort due to shingles was 61 percent lower
than in placebo recipients.
Moreover, the zoster vaccine reduced the incidence
of postherpetic neuralgia (PHN)--a form of chronic nerve pain that is
the most common serious complication of shingles--by two-thirds compared
with placebo. The vaccine was well tolerated, with the rates of serious
adverse events low and local reactions at the vaccination site generally
mild.
"As people live longer, and the proportion of older
people in our population increases, it is highly likely that the
prevalence of shingles will increase. A preventive shingles vaccine
would be an enormous boon for the health and quality of life of
seniors," says Anthony S. Fauci, M.D., NIAID director. "We are extremely
gratified that this public-private partnership has led to these exciting
results, which have the potential to greatly benefit seniors in years to
come."
Approximately 12 percent of older people with
shingles experience pain lasting for 3 months or longer (the definition
of PHN used in the study). As people age, however, shingles-associated
nerve pain increases in frequency and severity. This complication may
occur in nearly one-third of persons with shingles who are 60 years of
age or older.
Patients with PHN often describe the pain as
burning, throbbing, aching, stabbing or shooting, and it can cause both
physical and emotional suffering. What can be most distressing and
debilitating, according to these patients, is that at least 90 percent
of them have allodynia--pain caused by something that ordinarily is not
painful, such as clothing touching the skin, or a cool breeze. Simply
dressing and having a shirt touch the side of the body that is affected
can be excruciating.
Postherpetic neuralgia is difficult to treat.
Antiviral medications can speed the healing of shingles and reduce the
severity of nerve damage caused by the disease, but only if these
medications are used within 72 hours of the first sign of a shingles
rash. Thus, it is important for people to recognize the symptoms of
shingles and get to a doctor quickly. Antiviral medications do not help
relieve PHN once it has begun.
The researchers emphasize that the zoster vaccine
was tested only as a preventive therapy and is not intended as a
treatment for those who already have shingles or postherpetic neuralgia.
On April 25, Merck announced that it had submitted a license application
to the Food and Drug Administration for the zoster vaccine. If approved
for use, the research team estimates the vaccine could prevent 250,000
cases of shingles that occur in the United States each year and
significantly reduce the severity of the disease in another 250,000
cases annually.
The study was funded by the VA and by Merck, which
supplied the vaccine and placebo. The James R. and Jesse V. Scott Fund
for Shingles Research provided additional funds.
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