Although immunization of varicella zoster virus (VZV)–seronegative solid organ transplant (SOT) patients using the live-attenuated varicella vaccine is generally contraindicated, use of the recombinant subunit herpes zoster vaccine (RZV) appears safe, according to a new study.

The report in the journal Transplantation points out that the product is indicated for VZV-seropositive persons to prevent shingles but could potentially also protect VZV-seronegative persons against varicella. Swiss researchers working with the CDC in Atlanta performed a safety and immunogenicity evaluation of RZV in VZV-seronegative SOT recipients as an option for protection.

Included in the study were 23 VZV-seronegative adult SOT patients with no history of varicella/shingles vaccine or disease; participants were given two doses of RZV vaccine 2 to 6 months apart. Median age was 38 years and median time since transplant procedure was 3.8 years among the patients with the most frequent transplant types being liver (35%) and lung (30%).  

Blood draws occurred prevaccination (V1), prior to the second dose (V2) and 4 weeks after the second dose (V3). Researchers evaluated humoral (anti-gE) and cell-mediated immunity, with polyfunctional cells defined as cells producing ≥2 cytokines.

Results indicate that median anti-gE levels significantly increased from V1 to V3 (P = 0001) and V2 to V3 (P <.0001), even though only 55% had a positive seroresponse. The authors point out that median polyfunctional CD4 T-cells counts increased from V1 to V2 (54/10 vs. 104/10 cells; P = .0041), and from V2 to V3 (380/10; P = .0002), with most adverse events mild and no rejection episodes.

“RZV was safe and elicited significant humoral and cellular responses in VZV-seronegative SOT patients and has the potential to be considered as a preventive strategy against primary varicella,” the researchers conclude.

Another study in the American Journal of Transplantation looked specifically at the safety and immunogenicity of RZV in lung-transplant recipients.

Canadian researchers and colleagues, including CDC representatives, note that lung-transplant recipients are at high risk for herpes zoster and that preventive measures are a significant unmet need.

The study team investigated the safety and immunogenicity of two doses of a recombinant zoster vaccine (RZV) in lung transplant recipients aged 50 years and older. Enrolled were 50 patients, 49 of whom received at least one vaccine dose.

Results indicate that Antiglycoprotein E (gE) antibody levels in 43 of them increased significantly compared with baseline (median optical density [OD] 1.96; interquartile range [IQR]: 1.17-2.89) after the first (median OD 3.41, IQR 2.54-3.81, P <.0001) and second vaccine dose (median OD 3.63, IQR 3.39-3.86, P <.0001). Researchers describe how gE-specific polyfunctional CD4+ T-cell frequencies in 38 participants also increased from baseline (median 85 per 106 CD4+ T-cells; IQR: 46-180) to the first (median 128 per 106 CD4+ T-cells; IQR: 82-353; P = 0.023) and after the second dose (median 361 per 106 CD4+ T-cells; IQR: 146-848; P <.0001).

In terms of adverse reactions, tenderness (83.0%; 95%CI:69.2-92.4%) and redness (31.9%; 95%CI:19.1-47.1%) at injection site were common, they write.

In addition, the study team observed one rejection episode within 3 weeks of vaccination.

“This is the first study demonstrating that RZV was safe and elicited significant humoral and cell mediated immunity in lung transplant recipients,” the authors conclude. “RZV is a new option for the prevention of shingles in this population.”

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