A new study published in the journal Annals of Internal Medicine reports that two doses of the recombinant zoster vaccine (RZV) remain effective four years after vaccination against Herpes Zoster (HZ).
The results of the prospective cohort study showed that individuals who received two doses of the vaccine exhibited a vaccine effectiveness (VE) of 79% in the first year, regardless of when they received their second dose, with effectiveness decreasing to 73% by the fourth year. In contrast, those who received a single dose showed a 70% effectiveness rate in the first year, decreasing to 52% by the fourth year.
The study, 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 health systems nationwide, also found that the effectiveness rate for those taking corticosteroids was 65%.
The researchers evaluated the incidence of HZ and monitored RZV status over time, determined by diagnosis and prescription of antiviral medication within 7 days of diagnosis.
Dr. Nicola Klein, MD, PhD, Director of the Vaccine Study Center at Kaiser Permanente in Oakland, California, who led the study, stated that the results may dispel concerns that waiting too long for the second dose reduces the effectiveness of the herpes vaccine.
Dr. Alexandra Tien, a primary care physician at Medical Associates of Rhode Island in Providence, emphasized the importance of the vaccine’s long-term effectiveness, especially as older adults are now living much longer than in previous years.
Currently, the CDC recommends two doses of RZV 2–6 months apart for patients over 50 years old. Adults over 19 years old who are immunocompromised should receive two doses of RZV 1–2 months apart.
According to Klein, studies have not shown whether RZV VE declines after 4 years. However, preliminary results of another study observing individuals in clinical trials found that VE values remained high even after 7 years.
The risk of HZ increases with age, and adults aged 85 years have a lifetime risk of 50%. Complications such as postherpetic neuralgia (PHN), characterized by persistent tingling, numbness, and disabling pain at the site of the rash, can affect the quality of life and functionality of older adults.
Dr. Tien noted that, as with any vaccine, patients may have concerns about potential side effects of RZV, but these effects, such as muscle pain, nausea, and fever, are mild compared to shingles.
The study was funded by the CDC through contracts with participating sites. The study’s authors reported no disclosures, and Dr. Tien did not disclose any conflicts of interest. Brittany Vargas is a journalist covering medicine, mental health, and wellness.