In older adults, is vaccination against herpes zoster effective and safe?
The herpes zoster (shingles) vaccine has demonstrated effectiveness in preventing shingles in older adults. Vaccination benefit was greater in persons 60 to 69 years of age than in those 70 years and older. Local injection site reactions were common. (Strength of Recommendation: A, based on consistent, good-quality, patient-oriented evidence.)
Herpes zoster results from reactivation of latent herpes zoster virus within the dorsal root ganglia. This reactivation typically results in a painful, localized, vesicular, and unilateral cutaneous eruption. The prodromal symptoms of headache, photophobia, malaise, localized abnormal skin sensations, and, rarely, fever may occur one to five days before the rash appears.1 In the United States, approximately 1 million new cases of herpes zoster occur annually, with an estimated 33% of the population developing the disease during their lifetime.2
This Cochrane review included eight randomized controlled trials with more than 52,000 participants. One-half of the trials directly compared herpes zoster vaccine with placebo. The largest study to measure the effectiveness of the vaccine in preventing the disease reported a median surveillance period of 3.12 years. In this study, which included more than 38,000 older adults, there was a significant reduction in confirmed cases of herpes zoster (risk ratio = 0.49; 95% confidence interval, 0.43 to 0.56). Among those 60 to 69 years of age, the number needed to treat to prevent one episode of shingles was 50, but the vaccine was less effective in those 70 years and older (number needed to treat = 100).
Adverse effects were reported more often in the vaccinated group than in the placebo group. In a meta-analysis performed using data from the four studies comparing vaccine with placebo, the incidence of injection site adverse effects such as erythema, pruritus, swelling, or warmth was significantly higher in the vaccinated group, with a number needed to treat to harm (NNTH) of 2.8. The risk of systemic adverse effects such as rash, fever, or hospitalization related to the vaccine was much lower (NNTH = 100) and was not statistically significant. This review also included a double-blind, randomized controlled trial comparing different concentrations of the herpes zoster vaccine with the 23-valent pneumococcal polysaccharide vaccine. Investigators found that the herpes zoster vaccine produced fewer injection site reactions, even at the highest concentration tested (risk ratio = 0.41; 95% confidence interval, 0.24 to 0.68).
Overall, the herpes zoster vaccine is safe, effective, and well tolerated, with primarily localized injection site reactions. The results of this review support the Advisory Committee on Immunization Practices recommendation that immunocompetent adults 60 years and older receive the vaccine, even if they have a history of herpes zoster.2