Two doses of recombinant zoster vaccine provides strong protection over 4 years even in immunocompromised patients

• Vaccine Effectiveness: The study involved nearly 2 million participants aged 50 years and older, contributing over 7.6 million person-years of follow-up. After adjustment for various factors, researchers found the overall vaccine effectiveness was 64% for one dose and 76% for two doses of RZV.

• Long-Term Protection: Individuals receiving two doses exhibited notable effectiveness, with a 73% protection rate against shingles after 3 to 4 years. In contrast, those with partial vaccination showed a lower efficacy of 52% after 4 years.

• Dose-Specific Effectiveness: The effectiveness of a single dose of RZV declined over time, ranging from 70% in the first year to 52% in the fourth year. Conversely, two fully administered doses maintained stronger protection, with rates around 73% across the third and fourth years.

The findings underscore the importance of complete vaccination, particularly the need for a second dose to enhance and sustain long-term protection against shingles. The research provides crucial real-world evidence supporting the current CDC recommendation of two doses of RZV for individuals aged 50 years and older, emphasizing its role in preventing shingles, especially among higher-risk populations.

The study acknowledges certain limitations, primarily its focus on individuals with health insurance, potentially limiting the broader representation of other demographics. Additionally, the observed effectiveness in this study was slightly lower than previous clinical trials, possibly due to less specific case confirmation methods used in this real-world setting.

Dr. Zerbo and colleagues concluded that the declining effectiveness of a single dose after the first year reinforces the necessity of the second dose. The study advocates for continued vaccination efforts, highlighting the sustained benefits of a two-dose regimen in reducing the risk of shingles among older adults.

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