A new vaccine that could put the pox on shingles for many adult sufferers of the often painful infection caused by the chickenpox virus has received federal approval, its manufacturer said Friday. Merck & Co. Inc. spokeswoman Christine Fanelle said the vaccine, Zostavax, was approved late Thursday by the Food and Drug Administration. The vaccine is only for adults who previously have had chickenpox. Shingles, also called herpes zoster, strikes when the chickenpox virus reactivates and resumes reproducing after lying dormant for decades in nerve cells in the body. There are roughly 1 million new U.S. cases of shingles each year. It typically affects the elderly, though anyone with a weakened immune system is vulnerable. Shingles can cause itching, burning and tingling, as well as a distinctive red rash that develops into pus-filled blisters that later break open and form scabs. Pain, too, is common and can persist in some patients for months or years. Merck research showed the vaccine reduced the incidence of shingles by half and pain and discomfort by nearly two-thirds. The vaccine’s long-term effectiveness remains unclear. Merck has shown that it works for at least four years, and plans to […]