How would you advise patients with known stable autoimmune thrombocytopenia regarding the Ad26.COV2.S (Johnson & Johnson/Janssen) vaccine?

For patients with autoimmune thrombocytopenia due to SLE, I favor avoiding vaccines that employ a viral vector due to concerns for viral induced lupus flare.

For patients with thrombocytopenia in association with antiphospholipid antibodies, would avoid the Johnson & Johnson (as well as Astra-Zeneca)...