Recently, reports of severe
thromboses,
thrombocytopenia, and
hemorrhage in persons vaccinated with the chimpanzee adenovirus-vectored
vaccine (
ChAdOx1 nCoV-19,
AZD1222,
Vaxzevria; Oxford/AstraZeneca) against severe acute respiratory syndrome coronavirus 2 have emerged. We describe an otherwise healthy 30-year-old woman who developed
thrombocytopenia,
ecchymosis, portal vein
thrombosis, and cerebral venous
sinus thrombosis the second week after she received the
ChAdOx1 nCoV-19 vaccine. Extensive diagnostic workup for
thrombosis predispositions showed heterozygosity for the
prothrombin mutation, but no evidence of myeloproliferative
neoplasia or infectious or
autoimmune diseases. Her only temporary risk factor was long-term use of
oral contraceptive pills (OCPs). Although both the
prothrombin mutation and use of OCPs predispose to portal and cerebral vein
thrombosis, the occurrence of multiple
thromboses within a short time and the associated pattern of
thrombocytopenia and
consumption coagulopathy are highly unusual. A maximum 4T
heparin-induced
thrombocytopenia (HIT) score and a positive immunoassay for anti-
platelet factor 4/
heparin antibodies identified autoimmune HIT as a potential pathogenic mechanism. Although causality has not been established, our case emphasizes the importance of clinical awareness. Further studies of this potentially new clinical entity have suggested that it should be regarded as a
vaccine-induced immune thrombotic
thrombocytopenia.