At least 17 cases of thrombosis and thrombocytopenia have been reported in patients who received the Johnson & Johnson COVID-19 vaccine in the United States.
Such events have been reported in patients who received the AstraZeneca vaccine as well.
What’s in a name?
- The phenomenon of vaccine-induced thrombosis and thrombocytopenia has been given different names, including:
- Vaccine-induced immune thrombotic thrombocytopenia (VITT)
- Vaccine-induced prothrombotic immune thrombocytopenia (VIPIT)
- Thrombosis and thrombocytopenia syndrome (TTS).
- Dr. Cuker’s preferred acronym is VITT.
- VITT is an immune-mediated reaction to the Johnson & Johnson and AstraZeneca vaccines that “results in thrombocytopenia and a strong propensity for thrombosis,” Dr. Cuker explained.
- Dr. Henry noted that VITT is reminiscent of heparin-induced thrombocytopenia (HIT).
- VITT appears to be “very rare,” but “we still don't have a great sense of how common it is” because additional cases may not have been recognized or have yet to present, Dr. Cuker said.
- VITT occurs about 5-30 days after vaccination.
- VITT appears to be mediated by IgG antibodies, which take time to build up.
- The exact mechanism is unknown, but VITT could be related to the adenovirus vector used in the Johnson & Johnson and AstraZeneca vaccines, Dr. Cuker said.
- The first 15 cases of VITT associated with the Johnson & Johnson vaccine occurred in women, and most patients were younger than 50 years of age.
- In Canada, where the AstraZeneca vaccine is available, cases of VITT have been reported in patients in their 80s and 90s.
- Symptoms of VITT can include severe, unrelenting headache; severe abdominal pain; nausea and vomiting; as well as typical signs and symptoms of deep vein thrombosis or pulmonary embolism.
- To determine if a patient has VITT, Dr. Cuker recommends ordering a disseminated intravascular coagulation panel – prothrombin time, partial thromboplastin time, fibrinogen, and D-dimer – as well as a standard HIT enzyme-linked immunosorbent assay (ELISA).
- Rapid immunoassays for HIT are not reliable for VITT, so HIT ELISA must be used, Dr. Cuker emphasized.
- Most patients with VITT have a “strongly positive” ELISA with optical density values “well in excess of 100 or 1.0,” depending on the scale, Dr. Cuker said.
Manage VITT like HIT
- Patients should receive an anticoagulant, but not heparin, Dr. Cuker said. It isn’t clear if heparin will be harmful in patients with VITT, but current guidelines recommend avoiding heparin.
- He also advised against using warfarin or vitamin K antagonists in patients with VITT “at least until their platelet count recovers.”
- High-dose intravenous immunoglobulin (e.g., 1 g/kg for 2 consecutive days) is recommended, as it is believed to interfere with platelet activation.
Show notes written by M. Alexander Otto, a reporter for MDedge and Medscape.
Dr. Henry has no relevant disclosures. Dr. Cuker has served as a consultant for Synergy Pharmaceuticals; has received authorship royalties from UpToDate; and his institution has received research support on his behalf from Alexion, Bayer, Novartis, Novo Nordisk, Pfizer, Sanofi, Spark Therapeutics, and Takeda.
* * *
For more MDedge Podcasts, go to mdedge.com/podcasts
Email the show: email@example.com
Interact with us on Twitter: @MDedgehemonc
David Henry on Twitter: @davidhenrymd