The efficacy of the zoster vaccine was lower in the Short-Term Persistence Substudy compared with the Shingles Prevention Study, researchers for the Shingles Prevention Study Group reported.
“The Shingles Prevention Study demonstrated that zoster vaccine reduced the herpes zoster burden of illness by 61.1%, the incidence of postherpetic neuralgia by 66.5% and the incidence of herpes zoster by 51.3% through 4 years of postvaccination follow-up,” the researchers wrote in Clinical Infectious Diseases. “The Short-Term Persistence Substudy extended the follow-up of this cohort of subjects to collect data on the persistence of zoster vaccine efficacy.”
The Short-Term Persistence Substudy (STPS) included 14,270 patients who were enrolled on the Shingles Prevention Study (SPS): 7,320 had received the vaccine and 6,950 had received placebo. The researchers assessed herpes zoster burden of illness, incidence of postherpetic neuralgia and the incidence of herpes zoster for the STPS, the two populations combined and each year for 7 years after vaccination.
In the STPS, the incidence of herpes zoster was 8.4 cases/1,000 person-years for vaccine recipients vs. 14 cases/1,000 person-years for placebo recipients. The vaccine efficacy for herpes zoster incidence decreased to 39.6%, from 51.3% in SPS. The vaccine efficacy for herpes zoster burden of illness decreased to 50.1%, from 61.1% in the SPS. The incidence of postherpetic neuralgia was 0.7/1,000 person-years in the vaccine group compared with 1.76/1,000 person-years in the placebo group. The vaccine efficacy for postherpetic neuralgia incidence decreased to 60.1%, from 66.5% in SPS.
“The duration of zoster vaccine efficacy is not know beyond 5 years after vaccination,” the researchers wrote. “The Long-Term Persistence Substudy, currently being analyzed, may provide additional data on the duration of zoster vaccine efficacy.”
Disclosure: The researchers report financial relationships with GlaxoSmithKline and Merck.