Public health experts were pleased last month when a study showed that GlaxoSmithKline's experimental shingles vaccine is much more effective than the established Merck vaccine.
In the long run, the prospect of a better shingles shot could improve vaccination rates among people 60 and older, now only at 24 percent.
But in the short run, the news creates a bit of a quandary: Should older adults who want protection wait, probably a few years, for approval of the new vaccine, and hope the herpes zoster virus doesn't cause its excruciating rash in the meantime?
"That's a hard question," said Stephanie Bialek, a herpes virus expert at the U.S. Centers for Disease Control and Prevention. "It's one we expect a lot of people to have."
Shingles is related to chickenpox. After chickenpox blisters disappear, the varicella-zoster virus goes dormant in nerve cells.
Years or decades later, the virus erupts as shingles in a quarter of infected adults, more than a million a year. People who live to 85 have a 50-50 chance of developing it.
Shingles can recur. The virus can even affect the eyes, a sight-threatening emergency called herpes zoster ophthalmicus. And about 10 percent of shingles sufferers are left with a complication called postherpetic neuralgia, a debilitating nerve pain.
Why the virus reactivates is unclear, but age-related declines in immune protection play a role because shingles usually occurs after age 50.