Table 1.

Time trends for IgG and IgA antibodies in both serum and saliva, overall sample and by previous SARS-CoV-2 exposure.

Variable, time	All subjects (n=60)		No previous SARS-CoV-2 (SN; n=50)		Previous SARS-CoV-2 (SP; n=10)		p-value2	p-value3
	Mean1	Δ (IC 95%)	Mean1	Δ (IC 95%)	Mean1	Δ (IC 95%)
Serum
Serum IgG (ng/ml)a
T0	0.04	-	0.01	-	3.7	-	0.005	0.45
T1	432.1	432.1 (219.3; 644.8)	255.6	255.6 (112.0; 399.2)	5962.2	5958.5 (-956.4; 12873.4)		0.11
T2	20373.65	20373.6 (11486.0; 29261.2)	17341.4	17341.4 (10262.7; 24420.1)	45603.0	45599.3 (14787.7; 76410.8)		0.08
Serum IgA (ng/ml)a
T0	0.02	-	0.01	-	0.1	-	<0.0001	0.24
T1	1.71	1.7 (0.01; 3.4)	1.10	1.1 (-0.1; 2.3)	16.1	16 (-22.2; 54.1)		0.44
T2	49.59	49.6 (21.1; 78.0)	61.6	61.6 (29.5; 93.7)	16.7	16.6 (-21.6; 54.9)		0.08
Saliva
Salivary IgG (ng/ml)a
T0	0.02	-	0.02	-	0.03	-	0.04	<0.0001
T1	0.07	0.1 (0; 0.1)	0.04	0.02 (-0.01; 0.06)	1.08	1.1 (-1.2; 3.3)		0.36
T2	10.8	10.8 (6.8; 14.8)	9.8	9.7 (4.1; 15.4)	18.1	18.1 (-7.2; 43.3)		0.53
Salivary IgA, (ng/ml)a
T0	0.02	-	0.02	-	0.02	-	0.22	0.06
T1	0.05	0.02 (0.01; 0.05)	0.04	0.02 (-0.01; 0.05)	0.06	0.04 (-0.02; 0.11)		0.59
T2	0.07	0.05 (0.02; 0.08)	0.06	0.04 (0.01; 0.07)	0.16	0.14 (-0.05; 0.32)		0.29

a: Change in geometric mean concentration, modelled through a log-linear regression model for repeated measures, with unstructured variance-covariance matrix and adjusting for baseline.

1: Geometric mean concentration

2: p-value testing homogeneity of trends between subjects with and without previous SARS-CoV-2 infection.

3: p-value testing homogeneity of geometric mean values in IgG and IgA between subjects with and without previous SARS-CoV-2 infection, at each time.