Accumulating evidence sugges ts solid organ transplant recipients, as opposed to the general population, show strongly impaired responsiveness toward standard SARS-CoV-2 mRNA-based vaccination, demanding alternative strategies for protectio n o f this vulnerable group.

In line with recent recommendations, a third dose of either heterologous ChAdOx1 (AstraZeneca) or homologous BNT162b2 (BioNTech) was administered to 25 kidney transplant recipients (KTR) without humoral response after two doses of BNT162b2, followed by analysis of serological responses and vaccine-specific B- and T-cell immunity.

Nine out of 25 (36%) KTR under standard immunosuppressive treatment seroconverted until day 27 after the third vaccination, whereas one patient developed severe COVID-19 infection immediately after vaccination. Cellular analysis 7 days after the third dose showed significantly elevated frequencies of viral spike-protein receptor-binding domain-specific B cells in humor al responders as compared with nonresponders. Likewise, portions of spike-reactive CD4⁺ T helper cells were significantly elevated in patients who were seroconverting. Furthermore, overall frequencies of IL-2⁺, IL-4⁺, and polyfunctional CD4⁺ T cells significantly increased after the third dose, whereas memory/effector differentiation remained unaffected.

Our data suggest a fraction of transplant recipients benefit from triple vaccination, where seroconversion is associated with quantitative and qualitative changes of cellular immunity. At the same time, the study highlights that modified vaccination approaches for immunosuppressed patients remain an urgent medical need.

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越来越多的证据表明，与普通人群相比，实体器官移植受者对标准的基于 SARS-CoV-2 mRNA 的疫苗接种的反应严重受损，需要替代策略来保护这一弱势群体。

根据最近的建议，第三剂异源 ChAdOx1（AstraZeneca）或同源 BNT162b2（BioNTech）对 25 名肾移植受者（KTR）进行了两次剂量 BNT162b2 后无体液反应，随后分析了血清学反应和疫苗-特异性 B 细胞和 T 细胞免疫。

在标准免疫抑制治疗下，25 名（36%）KTR 患者中有 9 名在第三次接种疫苗后的第 27 天出现血清转化，而一名患者在接种疫苗后立即发生严重的 COVID-19 感染。第三次给药后 7 天的细胞分析显示，与无应答者相比，体液应答者中病毒刺突蛋白受体结合域特异性 B 细胞的频率显着升高。同样，血清转化患者的尖峰反应性 CD4 ^{+ T 辅助细胞部分显着升高。}此外，IL-2 ⁺、IL-4 ⁺和多功能 CD4 ⁺ T 细胞的总体频率在第三次给药后显着增加，而记忆/效应分化保持不受影响。

我们的数据表明，一小部分移植受者受益于三联疫苗接种，其中血清转化与细胞免疫的定量和定性变化有关。同时，该研究强调，针对免疫抑制患者改进的疫苗接种方法仍然是一项紧迫的医疗需求。

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