Shingles vaccine proves
effective in large trial
In one of the largest adult vaccine trials ever, researchers from the University of Colorado Denver have shown that an experimental
vaccine against shingles prevented about 51 percent, of cases of shingles – a
painful nerve and skin infection – and dramatically reduced its severity
and complications in vaccinated persons who got shingles. The findings
appeared in the June 2 edition of the New England Journal of Medicine.
The medical term for shingles is herpes zoster. Shingles is caused by reactivation
of the virus that caused chickenpox, which persists in a dormant state within
nerve cells in everyone following a childhood infection. Shingles is characterized
by pain in one area of skin on one side of the body or face, and by a painful,
blistering rash in the same area of skin. It can afflict anyone who has had
chickenpox – which includes most adults in the United States. Half
of people who live to age 85 will get shingles, and it is estimated that
more than one million new cases of shingles occur in the United States each
year.
“For some people, shingles can result in months or even years of misery,” said
local investigator Myron Levin, MD, professor of pediatric infectious diseases
at UCD and one of the study’s authors.
Shingles and a complication called postherpetic neuralgia (PHN), consisting
of pain originating in damaged nerves that can persist for months or years,
can diminish the quality of life and functional capacity of older adults,
and markedly reduce their enjoyment of life.
The Shingles Prevention Study involved more than 38,500 men and women, age
60 or older at 22 study sites across the United States, including 16 VA medical
centers and six clinical sites coordinated through the National Institute
of Allergy and Infectious Diseases (NIAID).
The vaccine used in the study is called “zoster vaccine.” Half
of the subjects received a placebo and the other half received a single injection
of the zoster vaccine - containing a live, weakened form of varicella-zoster
virus, the virus responsible for chickenpox and shingles. The zoster vaccine,
manufactured by Merck & Co., Inc., is a new, higher potency version of
the vaccine that has been used to prevent chickenpox in children since 1995.
The new zoster vaccine was developed for and studied in older adults.
During an average of more than three years of follow-up, 642 cases of shingles
occurred in the placebo group, compared to only 315 in the vaccinated group.
The total burden of pain and discomfort caused by shingles was reduced by
61 percent, or nearly two-thirds, in vaccine recipients compared with placebo
recipients. Moreover, vaccinated subjects were only a third as likely as
placebo recipients to develop PHN.
“The zoster vaccine was able to prevent shingles, or convert it to a minor
illness,” said Levin.
Approximately 1 in 8 (12 percent) of older people with shingles experience
pain lasting for 3 months or longer. At least 90 percent of patients with
PHN have allodynia – pain caused by something that is not ordinarily
painful, such as clothing touching the skin or a cool breeze – one
of the most distressing and debilitating types of pain.
“If the side of your body is affected by shingles, just the touch of a
shirt can be painful,” said Levin. “If you have shingles on your
head, even a breeze can be intolerable.”
Postherpetic neuralgia is notoriously difficult to treat,” added Levin,
noting that patients with PHN often describe the pain as burning, throbbing,
aching, stabbing, or shooting. Antiviral medications have been shown to speed
the healing of shingles and reduce the severity of nerve damage caused by
the disease, but only if they were used within 72 hours of the first sign
of the 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 zoster vaccine reduced the incidence of PHN by two-thirds (66 percent)
compared to placebo. The only adverse experiences reported significantly
more often by vaccine recipients than placebo recipients were headaches and
injection-site reactions such as redness, tenderness, swelling and rash.
Most of these adverse experiences were reported as mild in intensity. The
researchers emphasized that the zoster vaccine was tested only as a preventive
therapy. It is not intended as a treatment for those who already have shingles
or postherpetic neuralgia.
The Shingles Prevention Study was a VA Cooperative Study carried out in collaboration
with the NIAID and Merck & Co., Inc. The study was funded by the VA and
Merck & Co., Inc., which supplied the vaccine and placebo. Additional
funds were provided by the James R. and Jesse V. Scott Fund for Shingles
Research.
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