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Herpes zoster subunit vaccine efficacious in older adults
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Herpes zoster subunit vaccine with adjuvant reduces the risk for shingles and postherpetic neuralgia in patients aged 70 years or older, according to a recent international phase 3 trial.
“The overall incidence of herpes zoster is 2 to 4.6 cases per 1,000 person-years but increases with age to 10 to 12.8 per 1,000 person-years among persons 80 years of age or older,” Anthony L. Cunningham, MD, director of the Westmead Institute for Medical Research, and research medicine professor at Sydney Medical School, Australia, and colleagues wrote. “Antiviral therapy can reduce the duration of herpes zoster rash but has not been shown to decrease the incidence of postherpetic neuralgia. Vaccination is therefore an attractive option to reduce the disease burden due to herpes zoster and its complications in older adults.”
In a previously published study conducted among adults aged 50 years or older, a herpes zoster subunit vaccine (HZ/su) containing varicella-zoster virus (VSV) glycoprotein E and a novel adjuvant conferred protection to 97.2% of study participants, Cunningham and colleagues wrote. To assess the effectiveness of HZ/su in an older population, the researchers randomly assigned adults aged 70 years or older from 18 countries to receive either two-dose HZ/su or placebo. They excluded all adults with a history of herpes zoster, previous varicella or HZV vaccination, or an immunosuppressive condition. Cunningham and colleagues analyzed vaccine efficacy between vaccine recipients and controls, and repeated the analysis after pooling participants from the previous trial who also were aged at least 70 years. The researchers also examined the incidence of postherpetic neuralgia, vaccine safety and vaccine reactogenicity.
There were 13,900 participants included in the primary analysis, and 16,596 included in the pooled analysis. Twenty-three HZ/su recipients of the primary analysis developed herpes zoster during a mean follow-up period of 3.7 years as opposed to 223 participants in the control arm (0.9 per 1,000 person-years vs. 9.2 per 1,000 person-years), translating to an 89.8% vaccine efficacy (95% CI, 84.2-93.7). Stratification by age group did not significantly affect efficacy.
In the pooled analysis, vaccine efficacy was 91.3% against herpes zoster (95% CI, 86.8-94.5) and 88.8% against postherpetic neuralgia (95% CI, 68.7-97.1). Incidence of serious adverse events including death was similar between study groups, although reports of injection-site and systemic reactions within 7 days of injection were more frequent among HZ/su recipients.
Kathleen M. Neuzil
“As we found in adults 50 years of age or older, the efficacy of HZ/su indicates that immune responses directed against a single VSV antigen are capable of protecting against herpes zoster in adults 70 years of age or older,” Cunningham and colleagues.
In a related editorial, Infectious Disease News Editorial Board member Kathleen M. Neuzil, MD, MPH, director of the Center for Vaccine Development at the University of Maryland School of Medicine, and Marie R. Griffin, MD, MPH, professor of health policy and medicine at Vanderbilt University, warned against taking these results at face value. Higher rates of efficacy than reported for the live-attenuated vaccine could indicate a less frail population or less stringent case definition, while other issues affecting vaccine uptake still affect the newer formulation.
“The reasons for continued poor uptake include provider challenges, limited public awareness of the disease and vaccine, a lack of requirements for adult vaccination and the focus on acute medical care over prevention among practitioners caring for adult patients,” they wrote. “Although HZ/su may address some of these issues, such as easier storage requirements for a nonreplicating product, it will have its own challenges, including the two-dose schedule and the higher reactogenicity. Thus, the full public health value of herpes zoster vaccines will not be realized unless we identify and address barriers to delivery and uptake.” – by Dave Muoio
Disclosures: Cunningham reports receiving consulting fees from BioCSL/Sequirus, the GlaxoSmithKline group of companies and Merck, all paid to his institution. Griffin and Neuzil report no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.
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