McMaster University, Hamilton Health Sciences, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada.
Semin Hematol. 2022 Apr;59(2):72-75. doi: 10.1053/j.seminhematol.2022.02.002. Epub 2022 Feb 8.
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a life-threatening syndrome of aggressive thrombosis, often profound thrombocytopenia, and frequently overt disseminated intravascular coagulation. It has been associated with 2 adenovirus vector COVID-19 vaccines: ChAdOx1 nCoV-19 (AstraZeneca) and Ad26.COV2.S (Janssen). Unlike the myriad of other conditions that cause thrombosis and thrombocytopenia, VITT has an important distinguishing feature: affected individuals have platelet activating anti-PF4 antibodies that appear in a predictable time frame following vaccination. The reported incidence of VITT differs between jurisdictions; it is dependent on accurate ascertainment of cases and accurate estimates of the size of the vaccinated population. The incidence ranges from 1 case per 26,500 to 127,3000 first doses of ChAdOx1 nCoV-19 administered. It is estimated at 1 case per 518,181 second doses of ChAdOx1 nCoV-19 administered, and 1 case per 263,000 Ad26.COV2.S doses administered. There are no clear risk factors for VITT, including sex, age, or comorbidities. VITT is a rare event, but its considerable morbidity and mortality merit ongoing pharmacovigilance, and accurate case ascertainment.
疫苗诱导的免疫性血栓性血小板减少症（VITT）是一种危及生命的侵袭性血栓形成综合征，常伴有严重血小板减少症，并常伴有明显的弥漫性血管内凝血。它与 2 种腺病毒载体 COVID-19 疫苗有关：ChAdOx1 nCoV-19（阿斯利康）和 Ad26.COV2.S（杨森）。与引起血栓形成和血小板减少的其他无数情况不同，VITT 具有一个重要的特征：受影响的个体具有血小板激活的抗 PF4 抗体，这些抗体在接种疫苗后可在可预测的时间范围内出现。VITT 的报告发病率在不同司法管辖区有所不同；它取决于对病例的准确确定以及对接种人群规模的准确估计。ChAdOx1 nCoV-19 首剂接种的发病率从每 26500 例 1 例到每 1273000 例不等。估计每接种 518181 剂 ChAdOx1 nCoV-19 就有 1 例，每接种 263000 剂 Ad26.COV2.S 就有 1 例。VITT 没有明确的危险因素，包括性别、年龄或合并症。VITT 是一种罕见事件，但它相当高的发病率和死亡率值得持续进行药物警戒，并对病例进行准确确定。
