People who received the two-dose Shingrix vaccine had an 88% lower risk of developing shingles in the fourth year after vaccination, compared with a 91% reduction over the entire period of the trial.
In adults age 70 and older, two doses of the vaccine demonstrated 90% efficacy compared with a placebo.
A previous study in people age 50 and over showed that the vaccine was 97% effective compared with a placebo.
GSK said the risk of severe adverse events, potential immune-mediated diseases or deaths observed in phase III ZOE-70 study was similar in people receiving Shingrix and placebo.
The company is planning to file regulatory applications this year.
GSK senior vice president of vaccines research and development Emmanuel Hanon said: “This is the first time that such high efficacy has been demonstrated in a vaccine candidate for older people and it is remarkable, as we know that these people frequently have an age-related weakening of their immune system.
“If approved, this candidate vaccine could be an important tool for the prevention of shingles and the pain associated with it, which would significantly impact the health and quality of life of so many people.”
Shingrix is a non-live, adjuvanted, subunit (HZ/su) candidate vaccine indicated to help in avoiding herpes zoster and its complications.
It combines glycoprotein E, a protein identified on the varicella zoster virus (VZV) that causes shingles, with an adjuvant system, AS01B, which aims to improve the immunological response to the antigen.
The company is undertaking further trials to assess the ability of Shingrix to help prevent shingles in healthy people aged 50 and more and in adults with compromised immune systems.