Nadja Vielot, PhD, an epidemiologist in the UNC Department of Family Medicine, is lead author of a newly published study in Annals of Internal Medicine that provides real-world evidence for the effectiveness of the recombinant zoster vaccine (RZV) in older adults.
The research team conducted a target trial emulation using Medicare claims data from 2007 to 2019 to assess the effectiveness of RZV, the current vaccine recommended for the prevention of shingles, among adults aged 65 and older, including those previously vaccinated with the live zoster vaccine (ZVL). The study found that two doses of RZV offer significantly greater protection against shingles than one dose, and that the vaccine is effective even when the second dose is delayed.
“Clinical trials show how vaccines work under ideal conditions, but we need real-world data to understand how they perform when people miss doses or get vaccinated outside recommended intervals,” said Dr. Vielot. “Our study shows that two doses of RZV – even if delayed – provide statistically significant protection against shingles. That’s a message providers need to share with patients.”
The study found that one dose of RZV was 56.1% effective against shingles, while two doses increased protection to 67.9%. Effectiveness was consistent across age groups and among immunocompromised individuals. Patients who had previously received ZVL still benefited from RZV, though slightly less than those without prior ZVL. Importantly, the second dose was effective whether administered within the CDC-recommended window or later.
The findings underscore the importance of completing the two-dose series, even if the second dose is delayed due to supply shortages or patient hesitancy. The study also highlights the value of real-world data in capturing vaccine performance among populations often excluded from clinical trials, including individuals undergoing cancer treatment or living with autoimmune conditions. Medicare data also offered a broader representation of Black Americans, who are less likely to get shingles but are often underrepresented in vaccine research.
“It’s especially important for immunocompromised patients to receive both doses,” Dr. Vielot added. “They’re at higher risk for shingles, and our data shows the vaccine works just as well for them.”
The study is available at Annals of Internal Medicine and was also covered by Medscape: Second Dose Boosts Shingles Protection in Adults Aged ≥65 Years.
Other UNC contributors to the study include Sylvia Becker-Dreps, MD, MPH; Jennifer L. Lund, PhD; David J. Weber, MD, MPH; Jennifer S. Smith, PhD; and Michael G. Hudgens, PhD.