Once a person has had chickenpox, the virus lies inactive in nerve tissue. Years later, it may reactivate as shingles. The C.D.C. estimates that about one million cases are diagnosed in the United States each year.
“This is what we’ve been waiting for,” said Dr. Anne Louise Oaklander, an associate professor of neurology at Harvard Medical School and an expert in the disease. “Shingles is an unappreciated and common cause of severe problems throughout the nervous system.”
Dr. Oaklander said that while rash symptoms lead some people to consider shingles as minor as a bad sunburn, the illness can cause strokes, encephalitis, spinal cord damage and loss of vision.
Given in one dose, Zostavax had shown a 51 percent reduction in shingles and a 67 percent reduction in nerve pain. Shingrix is given in two doses, and the company said clinical trials showed it to be about 98 percent effective for one year and about 85 percent over three years.
By preventing shingles, the vaccine also drastically reduces the overall incidence of severe nerve pain, a lasting complication for about one in three people who get shingles. GlaxoSmithKline said it tested the vaccine in more than 38,000 people.
“We believe Shingrix will provide confidence in the protection one can expect from a shingles vaccine,” said Luc Debruyne, the company’s president of global vaccines.
The recommendation of the advisory committee will be considered an endorsement of Shingrix over Zostavax, although the closeness of the committee vote, 8 to 7, may mitigate the market loss for Merck.
Dr. Kathleen Dooling, a medical officer in the C.D.C.’s division of viral disease, said she expected the agency’s final recommendation to be issued early next year.
“The Shingrix vaccine has the potential to prevent tens of thousands of cases of shingles and its complications,” Dr. Dooling said.
She cautioned, however, that more people had adverse reactions to Shingrix than to Zostavax, including fever and muscle aches.
“Patients and health care providers should be aware that this vaccine is very effective, but it also causes more reactions than they may be used to with other adult vaccines,” she said. “All indications are these are not dangerous to one’s health, but they may interfere with your daily activities for a few days.”
GlaxoSmithKline said its new vaccine would cost about $280 and would be available next month. Zostavax costs about $223.