A new vaccine for shingles, a painful infection caused by the chickenpox virus, has been approved in the U.S., health officials said Friday.

Merck & Co. Inc., manufacturer of the vaccine Zostavax, said the U.S. Food and Drug Administration gave its approval late Thursday.

The same virus causes chickenpox in children and shingles in adults.
CBC

The vaccine is intended only for adults 60 years of age and older who previously have had chickenpox.

An outbreak of shingles occurs when the chickenpox virus reactivates after lying dormant in nerve cells, sometimes for decades, and starts reproducing again.

Shingles, also called herpes zoster, causes a painful red rash and sensations of tingling, itching and burning. The rash can lead to scarring and the pain can persist in some people for months or years.

Up to 20 per cent of adults who have had chickenpox will get shingles later in life.

The long-term effectiveness of the vaccine isn't clear. Merck's research shows that it works for at least four years and the company plans to follow patients for 10 years to track effectiveness.