Two doses of the recombinant zoster vaccine (RZV) are effective against herpes zoster (HZ) for 4 years after vaccination, according to a new study published in the Annals of Internal Medicine.
Findings from the prospective cohort study showed that people who received two doses of the vaccine, regardless of when they received their second dose, experienced 79% vaccine effectiveness (VE) during the first year, with effectiveness decreasing to 73% by year 4. By contrast, the rate of effectiveness during the first year was 70% for people who received a single dose, falling to 52% effectiveness by year 4.
The findings also showed that the rate of effectiveness was 65% for those taking corticosteroids.
The study was conducted between 2018 and 2022 using data from the Vaccine Safety Datalink, a collaboration between the US Centers for Disease Control and Prevention (CDC) and nine healthcare systems across the country.
Researchers evaluated the incidence of HZ, as determined by a diagnosis and prescription for antiviral medication within 7 days of diagnosis, and monitored RZV status over time.
The findings may quell fears that waiting too long for the second dose reduces the effectiveness of the herpes vaccine, according to Nicola Klein, MD, PhD, director of the Vaccine Study Center at Kaiser Permanente in Oakland, California, who led the study.
The long-term efficacy of the vaccine is especially important because older adults are now living much longer than in previous years, according to Alexandra Tien, MD, a family physician at Medical Associates of Rhode Island in Providence.
“People live these days into their 80s and even 90s,” Tien said. “That’s a large number of years to need protection for, so it’s really important to have a long-lasting vaccine.”
The CDC currently recommends two doses of RZV separated by 2-6 months for patients aged 50 years and older. Adults older than 19 years who are immunocompromised should receive two doses of RZV separated by 1-2 months, the agency said.
According to Klein, research does not show whether VE for RZV wanes after 4 years. But interim findings from another study following people in clinical trials found VE levels remained high after 7 years.
The risk for HZ increases with age, reaching a lifetime risk of 50% among adults aged 85 years. Complications like postherpetic neuralgia (PHN) — characterized by long-term tingling, numbness, and disabling pain at the site of the rash — can interfere with the quality of life and ability to function in older adults. The CDC estimates that up to 18% of people with shingles experience PHN, and the risk increases with age.
Just like with any other vaccine, patients sometimes have concerns about the potential side effects of RZV, said Tien. But those effects, such as muscle pain, nausea, and fever, are mild compared to shingles.
“I always tell patients, with any vaccine, immunization is one of the biggest bangs for your buck in healthcare because you’re preventing a problem,” Tien said.
This study was funded by the CDC through contracts with participating sites. Study authors reported no disclosures. Tien reported no disclosures.
Brittany Vargas is a medicine, mental health, and wellness journalist.
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