Table 3.

Median Semiquantitative SARS-CoV-2 Anti-Spike Antibody Immunoassay Results of Heart and Lung Transplant Recipients by Antibody Response

	D1		D2
	Roche Elecsys	EUROIMMUN	Roche Elecsys	EUROIMMUN
	U/mL (IQR)	(IQR)	U/mL (IQR)	(IQR)
	n = 183	n = 54	n = 183	N = 54
Priming dose responders	2.9 (1.1, 11.5)	2.4 (2.3, 2.5)	250 (174, 250)	9.1 (7.2, 9.4)
Booster responders	0 (0, 0)	0.2 (0.03, 0.5)	23.8 (3.9, 244.2)	5.5 (2.1, 8.0)
Non-responders	0 (0, 0)	0.1 (0.03, 0.2)	0 (0, 0)	0.2 (0.1, 0.5)

Anti-RBD immunoassay (Roche Elecsys) results are reported as a concentration of immunoglobulin G (IgG) against the target protein with a measurement range of 0.4 to 250 U/mL; results ≥250 U/mL are reported as 250 U/mL. Anti-S1 immunoassay (EUROIMMUN) results are reported as a sample-to-control ratio of optical density. Antibody-positive cut-offs (determined by the manufacturer) were ≥0.80 U/mL for the former and ≥1.1 arbitrary units for the latter. Priming dose responders developed positive results after both D1 and D2. Booster responders developed positive results only after D2. Non-responders maintained negative results after D1 and D2. D1/D2; Dose1/2. RBD; Receptor binding domain.