The long-term clinical efficacy of SARS-CoV-2 vaccines according to antibody response in immunosuppressed patients such as hematological patients has been little explored. A prospective multicenter registry-based cohort study conducted from December 2020 to July 2022 by the Spanish Transplant and Cell Therapy group, was used to analyze the relationship of antibody response over time after full vaccination (at 3–6 weeks, 3, 6 and 12 months) (2 doses) and of booster doses with breakthrough SARS-CoV-2 infection in 1551 patients with hematological disorders. At a median follow-up of 388 days after complete immunization, 266 out of 1551 (17%) developed breakthrough SARS-CoV-2 infection at median of 86 days (range 7–391) after full vaccination. The cumulative incidence was 18% [95% confidence interval (C.I.), 16–20%]. Multivariate analysis identified higher incidence in chronic lymphocytic leukemia patients (29%) and with the use of corticosteroids (24.5%), whereas female sex (15.5%) and more than 1 year after last therapy (14%) were associated with a lower incidence (p < 0.05 for all comparisons). Median antibody titers at different time points were significantly lower in breakthrough cases than in non-cases. A serological titer cut-off of 250 BAU/mL was predictive of breakthrough infection and its severity. SARS-CoV-2 infection-related mortality was encouragingly low (1.9%) in our series. Our study describes the incidence of and risk factors for COVID-19 breakthrough infections during the initial vaccination and booster doses in the 2021 to mid-2022 period. The level of antibody titers at any time after 2-dose vaccination is strongly linked with protection against both breakthrough infection and severe disease, even with the Omicron SARS-CoV-2 variant.
关于SARS-CoV-2疫苗在免疫抑制患者（如血液病患者）中基于抗体反应的长期临床疗效研究较少。西班牙移植与细胞治疗组于2020年12月至2022年7月开展了一项基于注册的前瞻性多中心队列研究，分析了1551例血液疾病患者完成全程疫苗接种（2剂）后不同时间点（3–6周、3个月、6个月及12个月）的抗体反应及加强针接种与突破性SARS-CoV-2感染的关系。在完成全程免疫后中位随访388天内，1551例患者中有266例（17%）发生突破性感染，中位感染时间为全程接种后86天（范围7–391天）。累计发生率为18%[95%置信区间(C.I.) 16–20%]。多变量分析显示慢性淋巴细胞白血病患者（29%）和使用皮质类固醇者（24.5%）发生率更高，而女性（15.5%）及末次治疗超过1年者（14%）发生率较低（所有比较p<0.05）。突破性感染病例在各时间点的抗体滴度中位数均显著低于未感染病例。血清抗体滴度临界值250 BAU/mL对突破性感染及其严重程度具有预测价值。本系列研究中SARS-CoV-2感染相关死亡率较低（1.9%），结果令人鼓舞。本研究描述了2021年至2022年中期初始疫苗接种和加强针接种期间COVID-19突破性感染的发生率及风险因素。在接种2剂疫苗后的任何时间点，抗体滴度水平均与预防突破性感染和重症密切相关，即使面对奥密克戎SARS-CoV-2变异株亦是如此。
肿瘤(癌症)患者之家