2. Test sensitivity by time since onset of symptoms.

	Days 1‐7	Days 8‐14	Days 15‐21	Days 22‐35	Days > 35	Comparison
	Test groups [studies] (true positives/COVID cases) Sensitivity (95% CI)
IgG	33 [23] (165/568)	34 [22] (766/1200)	34 [22] (974/1110)	20 [12] (417/502)	11 [4] (213/252)
	29.7% (22.1 to 38.6)	66.5% (57.9 to 74.2)	88.2% (83.5 to 91.8)	80.3% (72.4 to 86.4)	86.7% (79.6 to 91.7)	P < 0.00005
IgM	34 [24] (207/608)	32 [21] (724/1171)	32 [21] (800/1074)	19 [11] (378/507)	11 [4] 118/215
	23.2% (14.9 to 34.2)	58.4% (45.5 to 70.3)	75.4% (64.3 to 83.8)	68.1% (55.0 to 78.9)	53.9% (38.4 to 68.6)	P < 0.00005
IgA	4 [4] (54/100)	3 [3] (38/53)	3 [3] (66/68)	2 [2] (81/82)	1 [1] (23/23)
	28.4% (0.9 to 94.3)	78.1% (9.5 to 99.2)	98.7% (39.0 to 100)	98.7% (91.9 to 99.8)	100% (85.2 to 100)	*
Total antibodies	5 [4] (62/144)	6 [5] (220/247)	6 [5] (174/176)	4 [3] (11/19)	2 [1] (15/28)
	24.5% (9.5 to 50.0)	84.0% (64.1 to 93.9)	98.1% (90.1 to 99.6)	69.5% (34.8 to 90.7)	79.0% (49.8 to 93.4)	P < 0.00005
IgG/IgM	17 [9] (81/259)	21 [9] (441/608)	21 [9] (636/692)	16 [5] (146/152)	9 [2] (122/153)
	30.1% (21.4 to 40.7)	72.2% (63.5 to 79.5)	91.4% (87.0 to 94.4)	96.0% (90.6 to 98.3)	77.7% (66.0 to 86.2)	P < 0.00005
IgA/IgG	1 [1] (0/12)	1 [1] (5/10)	1 [1] (7/8)	1 [1] (1/1)	0 [0]
	0% (0 to 26.5)	50.0% (18.7 to 81.3)	87.5% (47.3 to 99.6)	100% (2.5 to 100)		*
IgA/IgM	0 [0]	0 [0]	0 [0]	0 [0]	0 [0]
CI: confidence interval; * inadequate data to make a formal statistical comparison