Table 1.

Human serum ELISA IgG.

Serum	Days post symptom onset	Euroimmun IgG		Epitope IgG
		Index	Reactive	Index	Reactive
1	14	1.3	+	2.6	+
2	12	6.0	+	3.5	+
3	17	10.2	+	3.9	+
4	16	14.9	+	4.5	+
5	5	0.2	−	1.2	+
6	19	8.6	+	4.4	+
7	17	7.1	+	4.1	+
8	10	5.1	+	2.0	+
9	14	6.8	+	3.1	+
10	6	0.2	−	1.1	+
11	-	5.6	+	0.9	+/−
12	-	<0.8	−	1.3	+
13	9	0.7	−	1.1	+
14	20	3.6	+	2.9	+
15	13	0.4	−	2.0	+
16	13	0.5	−	0.9	−
17	11	0.3	−	0.8	−
18	10	0.2	−	0.7	−
19	14	0.9	+/−	1.2	+
20	10	0.4	−	1.5	+
21	11	0.5	−	2.0	+
22	10	0.3	−	0.6	−
23	17	7.6	+	4.2	+
24	14	3.5	+	3.3	+
25	13	1.5	+	2.9	+
26	17	14.2	+	4.4	+
27	13	0.5	−	1.9	+
28	14	9.2	+	4.6	+
29	13	3.9	+	2.8	+
30	16	3.4	+	4.6	+
31	15	10.7	+	3.6	+
32	6	0.5	−	1.1	+
33	11	0.4	−	1.8	+
34	12	0.6	−	2.5	+
35	14	3.7	+	4.1	+
36	20	11.6	+	4.2	+
37	7	0.7	−	1.2	+
38	8	1.7	+	1.9	+
39	7	0.3	−	0.7	−
40	9	3.4	+	2.2	+
41	18	10.3	+	4.1	+
42	17	10.3	+	4.6	+

Serum samples from 20 individuals were collected at different time points post onset of COVID-19 symptoms, were screened using two ELISA assays (Euroimmun or Epitope). The serum numbers correspond to those of Figures 4 and S3. IgG index values were calculated by dividing the O.D. of the serum sample by a reference O.D. control, and ratios were interpreted using the following criteria as recommended by the manufacturer: Negative (−) <0.8, Indeterminate (+/−) 0.8–1.1, Positive (+) ≥1.1.