During March 2 to April 21, 2021, there were 12 cases of cerebral venous sinus thrombosis (CVST) with thrombocytopenia reported after receipt of the Ad26.COV2.S (Janssen/Johnson & Johnson) COVID-19 vaccine, according to a case series reported in JAMA.

The Ad26.COV2.S COVID-19 vaccine uses a human adenoviral vector and received Emergency Use Authorization on February 27, 2021. In Europe, ChAdOx1 nCOV-19 vaccine (Oxford/AstraZeneca), which uses a chimpanzee adenoviral vector, was associated with CVST with thrombocytopenia.

Following 6 cases of CVST with thrombocytopenia among approximately 7 million recipients of Ad26.COV2.S vaccine in the US, on April 13, 2021, the Centers for Disease Control and Prevention and Food and Drug Administration recommended a pause in the use of the vaccine. By April 21, 6 additional cases of CVST with thrombocytopenia were reported to Vaccine Adverse Event Reporting System.

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The case series included 12 recipients of Ad26.COV2.S vaccine diagnosed with CVST and thrombocytopenia from March 2 to April 21, 2021. The objective was to report the clinical course, imaging findings, laboratory tests, and outcomes following diagnosis.

All 12 cases of CVST and thrombocytopenia occurred in women younger than 60 years. The median interval from vaccination to symptom onset was 8 days and ranged from 6 to 15 days. Headache on presentation was reported in 11 of 12 women. One patient initially presented with back pain and developed headache later.

Intracerebral hemorrhage was reported in 7 patients and nonCVST thromboses were reported in 8 women. Platelet nadirs ranged from 9×103/μL to 127×103/μL.

All patients included were hospitalized and 10 were admitted to an intensive care unit (ICU). Providers gave heparin to 6 patients diagnosed before public notification of CVST and thrombocytopenia events and all were subsequently changed to a nonheparin anticoagulant. 4 patients received nonheparin anticoagulant for CVST treatment initially, while 2 patients did not receive anticoagulants.

All antibody tests results were positive among the 11 patients with heparin-platelet factor 4 enzyme-linked immunosorbent assay (ELISA) heparin-induced thrombocytopenia (HIT).

At the time of the last follow-up, 3 patients died, all of whom had intraparenchymal hemorrhage and evidence of mass effect on initial head imaging. In addition, 3 patients continued ICU care, 2 continued non-ICU hospitalization, and 4 were discharged home.

Since April 21, 2021, 2 additional US reports to CVST with thrombocytopenia following administration of Ad26.COV2.S have been confirmed.

The case series had several limitations, including the retrospective design of medical record review, missing data on laboratory investigations, and using data from a passive surveillance system with potential under-reporting of CVST with thrombocytopenia.

“This case series may inform clinical guidance as Ad26.COV2.S vaccination resumes in the US as well as investigations into the potential relationship between Ad26.COV2.S vaccine and CVST with thrombocytopenia,” concluded the study researchers.


See I, Su JR, Lale A, et al. US case reports of cerebral venous sinus thrombosis with thrombocytopenia after Ad26.COV2.S vaccination, March 2 to April 21, 2021. JAMA. 2021. Published online April 30, 2021. doi:10.1001/jama.2021.7517