Two years ago, George Green got stabbing pain and bad blisters around his right arm. It was the worst case of shingles his doctor had ever seen.
"I said, 'Wait a minute, I had the vaccine! How come I got this?'" recalled Green, a 68-year-old engineer in Austell, Georgia, who got the shot seven years earlier.
His doctor at Emory University, Dr. Sharon Bergquist, said about 10 percent of the patients she's given the shingles shot have come back with the disease years later.
No vaccine is perfect, and it can take many years to find out how well a new vaccine works and how long it lasts. Sometimes, health officials have called for an additional dose when it became clear the first round wasn't cutting it. But disappointing performance is also prompting drugmakers to pursue new vaccines for older patients, using new additives to boost effectiveness.
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The issue of waning protection is expected to be discussed when the Advisory Committee on Immunization Practices meets in Atlanta. The two-day meeting opens Wednesday. The federal panel of experts recommends what vaccines children and adults should receive and when.