Long-term persistence of zoster vaccine efficacy

Area of Science:

• Immunology
• Vaccinology
• Epidemiology

Background:

• The Shingles Prevention Study (SPS) initially demonstrated zoster vaccine efficacy for 4 years.
• Subsequent studies confirmed vaccine effectiveness for at least 5 years.
• A Long-Term Persistence Substudy (LTPS) was initiated to evaluate efficacy up to 11 years post-vaccination.

Purpose of the Study:

• To assess the long-term persistence of zoster vaccine efficacy.
• To evaluate vaccine effectiveness for herpes zoster (HZ) burden of illness (BOI), postherpetic neuralgia (PHN) incidence, and HZ incidence.
• To analyze vaccine efficacy trends from year 7 to year 11 post-vaccination.

Main Methods:

• Follow-up of 6867 participants from the SPS vaccine group.
• Surveillance, case determination, and follow-up methods mirrored those of SPS and STPS.
• Modeled reference placebo groups were used due to vaccine availability to former placebo recipients.

Main Results:

• Vaccine efficacy decreased over the LTPS period (up to 11 years).
• Efficacy for HZ BOI decreased from 61.1% to 37.3%.
• Efficacy for PHN incidence decreased from 66.5% to 35.4%, and for HZ incidence from 51.3% to 21.1%.
• Statistically significant vaccine efficacy for HZ BOI persisted through year 10.
• Statistically significant vaccine efficacy for HZ incidence persisted only through year 8.

Conclusions:

• Zoster vaccine efficacy estimates declined over time in the LTPS.
• Significant vaccine efficacy for HZ burden of illness persisted into the 10th year post-vaccination.
• Significant vaccine efficacy for HZ incidence was observed only through the 8th year post-vaccination.