Table 1.

Clinical characteristics of iTTP episodes following COVID-19 vaccination

	All Median (range) or n (%)	Patient #1	Patient #2	Patient #3	Patient #4	Patient #5	Patient #6	Patient #7	Patient #8	Patient #9	Patient #10
	Age	57 (20-70)	36	54	60	60	38	68	66	70	22	20
Sex	Woman: 5 (50)	Woman	Man	Woman	Woman	Man	Man	Man	Woman	Man	Woman
Previous medical history		SLE	iTTP	iTTP			MCTDiTTP		Ischemic strokes, hypertension		SLE
Vaccine		BNT162b2	mRNA1273	BNT162b2	BNT162b2	BNT162b2	BNT162b2	ChAdOx1	ChAdOx1	BNT162b2	BNT162b2
								nCoV-19	nCoV-19
Dose	First: 8 (80)	First	First	First	First	Second	First	First	First	Second	First
Days since last dose	15 (6-30)	6	23	10	12	30	17	8	10	18	25
Type of episode	First: 7 (70)	First	Relapse	Relapse	First	First	Relapse	First	First	First	First
Years since last episode^*			19	27			6
Clinical presentation		Bruising, headache	Bruising, diffuse mucocutaneous bleeding, headache, amnesia	Cerebellar syndrome	Cerebellar syndrome, aphasia, confusion, chest pain	Fever, headache, hemiparesis, bruising	Dizziness	Facial paralysis	Comahemiparesis	Coma, seizures, purpura, fever	SLE Flare: polyarthritis, erythema
Biology at diagnosis
Hemoglobin, g/dL	8.0 (6.5-11.5)	10.0	11.5	10.8	6.5	6.6	10.9	7.9	8.0	6.8	5.3
Platelets, ×10⁹/L	14 (6-39)	10	17	27	20	9	39	11	6	10	51
Schistocytes, %	3 (1-6)	3	2	2	6	5	1	4	2	+	3
Creatinine, mg/dL	0.95 (0.76-1.70)	0.98	1.70	0.76	0.92	1.01	0.79	0.93	0.90	1.15	1.00
Troponin elevated^†	7 (70)	+	+	+	+	+	+	—	+	—	—
Fibrinogen, g/L	3 (2.4-6.7)	2,8	2.4	3.0	3.6	2.9	3.0	6.7	NA	NA	3.7
D-dimers, FEU	1571 (726-3768)	726	NA	NA	NA	3768	NA	1200	1942	NA	NA
ADAMTS13 activity, %		<5	<5	<10	5	<1	2	<5	11^‡	6	<10
Anti-ADAMTS13 Abs^§		0.5 BU/mL	1.1 BU/mL	+	52 U/mL	+	—	—	140 U/mL	+	50 U/mL
Anti-PF4 Abs		—	NA	—	NA	—	NA	—	—	—	NA
French score		2	2	2	2	2	1	2	2	2	1
Treatment
TPE (number)	4 (0-38)	8	3	3	3	38	4	5	0	17	0
Corticosteroids	10 (100)	+	+	+	+	+	+	+	+	+	+
Rituximab	8 (80)	+	+	+	—	+	+	+	+	+	—
Caplacizumab	6 (60)	—	+	—	+	+	+	+	+	—	—
Others	2 (20)	—	—	—	—	—	—	—	IVIg, plasma infusion^ǁ	—	Plasma infusion^ǁ
Outcome		Clinical remission	Clinical remission	Clinical remission	Clinical remission	Exacerbation under TPE, clinical remission	Clinical remission	Clinical remission	Death 2 mo after presentation	Clinical remission	Clinical remission
Rechallenge	1 (10)	0	0	0	0	0	0	+	0	0	0
Vaccine								BNT162b2

Abs, antibodies; BU, Bethesda units; FEU, fibrinogen equivalent units; IVIg, intravenous immunoglobulins; MCTD, mixed connective tissue disease; NA, not available; PF4, platelet factor 4; SLE, systemic lupus erythematosus; TPE, therapeutic plasma exchange; +, yes; —, no.

Due to the long delay since the last episode, these patients no longer had regular follow-up; consequently, no recent ADAMTS13 activity before vaccination is available.

^†

Defined as above the upper limit of normal value.

^‡

ADAMTS13 activity measurement was performed after initiation of immunosuppressive therapy.

^§

The presence of anti-ADAMTS13 antibodies was assessed either as the titer of total autoantibodies (inhibitory and noninhibitory) using an enzyme-linked immunosorbent assay expressed in arbitrary units (U/mL; the value of at least 25 U/mL was considered positive) or as the titer of inhibitory antibodies using a Bethesda assay expressed in Bethesda units (BU/mL), with 1 BU corresponding to the amount of inhibitor in 1 mL of plasma neutralizing 50% of ADAMTS13 activity of control levels (the value of at least 1.0 BU/mL was assumed to be positive).

^ǁ

In these 2 patients, TPE was omitted. Patient #8 was very comorbid and TPE was deemed too invasive. Hence, ADAMTS13 replacement was performed with plasma infusion only. In patient #10, initial presentation was a lupus flare with mild features of thrombotic microangiopathy. Initial treatment only included high-dose corticosteroids, leading to a rapid improvement of both lupus symptoms and thrombocytopenia. Later, ADAMTS13 activity confirmed the diagnosis of iTTP, and only plasma infusion was added to corticosteroids until complete remission.