Janssen Vaccines & Prevention B.V., Leiden, The Netherlands.
Janssen Research & Development, Beerse, Belgium.
J Thromb Haemost. 2024 Dec;22(12):3532-3541. doi: 10.1016/j.jtha.2024.08.019. Epub 2024 Sep 13.
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare adverse event identified following vaccination with some adenovirus-vectored COVID-19 vaccines, including Ad26.COV2.S. VITT is characterized by the presence of antibodies against platelet factor 4 (PF4).
To evaluate whether PF4 antibodies were generally induced following vaccination with adenovirus type 26 (Ad26)-vectored vaccines.
The study included 913 and 991 healthy participants without thromboembolic (TE) events in Ad26.COV2.S and non-COVID-19 Ad26-vectored vaccine clinical studies, respectively, and 1 participant with VITT following Ad26.COV2.S vaccination. PF4 antibody levels were measured in prevaccination and postvaccination sera. PF4 antibody positivity rates were assessed in a case-control setting in participants who developed TE events during participation in Ad26-vectored vaccine clinical studies.
In the 1 VITT patient, PF4 antibodies were negative before vaccination. Seroconversion for platelet-activating PF4 antibodies was observed upon Ad26.COV2.S vaccination. In participants without TE events, the PF4 antibody levels and positivity rates were similar before and after Ad26 vaccination. Ad26 vaccination did not increase PF4 antibody levels in participants who were PF4 antibody-positive at baseline (n = 47). Lastly, 1 out of 28 TE cases and 2 out of 156 non-TE controls seroconverted after Ad26.COV2.S vaccination. None of the 15 TE cases and 3 of the 77 non-TE controls seroconverted following non-COVID-19 Ad26 vaccination.
Ad26.COV2.S and the other Ad26-vectored vaccines studied did not generally induce PF4 antibodies or increase preexisting PF4 antibody levels. Moreover, unlike VITT, TE events that occurred at any time following Ad26 vaccination were not associated with PF4 antibodies.
疫苗诱导的免疫性血栓性血小板减少症（VITT）是在接种某些腺病毒载体 COVID-19 疫苗后发现的一种罕见不良反应，包括 Ad26.COV2.S。VITT 的特征是存在针对血小板因子 4（PF4）的抗体。
评估接种腺病毒 26 型（Ad26）疫苗后是否会普遍诱导 PF4 抗体。
该研究包括 913 名和 991 名在 Ad26.COV2.S 和非 COVID-19 Ad26 载体疫苗临床试验中无血栓栓塞（TE）事件的健康参与者，以及 1 名接种 Ad26.COV2.S 后发生 VITT 的参与者。在接种前和接种后血清中测量 PF4 抗体水平。在参加 Ad26 载体疫苗临床试验的参与者中发生 TE 事件的病例对照研究中评估 PF4 抗体阳性率。
在 1 例 VITT 患者中，接种前 PF4 抗体阴性。接种 Ad26.COV2.S 后观察到血小板激活的 PF4 抗体血清转化。在无 TE 事件的参与者中，接种 Ad26 前后 PF4 抗体水平和阳性率相似。在基线时 PF4 抗体阳性的参与者（n=47）中，Ad26 疫苗接种并未增加 PF4 抗体水平。最后，28 例 TE 病例中有 1 例和 156 例非 TE 对照中有 2 例在接种 Ad26.COV2.S 后发生血清转化。在接种非 COVID-19 Ad26 疫苗后，15 例 TE 病例中没有 1 例和 77 例非 TE 对照中没有 3 例发生血清转化。
Ad26.COV2.S 和研究中的其他 Ad26 载体疫苗通常不会诱导 PF4 抗体或增加预先存在的 PF4 抗体水平。此外，与 VITT 不同，在接种 Ad26 疫苗后的任何时间发生的 TE 事件与 PF4 抗体无关。
