“In a clinical trial involving thousands of adults 60 years old or older, Zostavax reduced the risk of shingles by about half (51%) and the risk of post-herpetic neuralgia by 67%. While the vaccine was most effective in people 60-69 years old it also provided some protection for older groups.Research suggests that the shingles vaccine is effective for at least six years, but may last longer. Ongoing studies are being conducted to determine how long the vaccine protects against shingles.”.. I am totally confused about the shingles vaccine. I was immunized three years ago at a cost of $220. Since I did not have insurance at the time I had to pay for the shot out of pocket. Now I read that protection from the vaccine wanes over time.