Table 4.

IgA antibody levels against SARS-CoV-2 in responders after infection and vaccination

	Infected			Vaccinated
	N		Median [IQR]	n		Median [IQR]	p-value
IgA antibody titres against RBD
Overall	52	2.97 [1.55; 7.37]		102	2.91 [1.61; 4.94]		0.39
KTR	17	7.09 [2.28; 10.09]		57	3.11 [1.75; 4.70]		0.009
HD	18	2.19 [1.45; 6.75]		38	2.99 [1.87; 6.64]		0.54
Control	17	2.64 [1.60; 5.08]		7	1.46 [1.20; 1.54]		0.01
IgA antibody titres against S1S2
Overall	60	5.82 [2.75; 14.10]		122	2.29 [1.41; 4.15]		< 0.001
KTR	19	12.41 [2.78; 21.10]		57	2.43 [1.57; 3.42]		< 0.001
HD	21	4.66 [2.54; 11.84]		50	2.29 [1.38; 4.32]		0.01
Control	20	4.41 [2.80; 8.05]		15	1.61 [1.24; 4.15]		0.004

Table showing the IgA antibody titres directed to RBD (upper panel) and S1S2 (lower panel) of SARS-CoV-2 in responders. Time from PCR or first vaccine to blood sample was not correlated with the IgA RBD titres (n = 154, r_s = 0.02, p = 0.82) nor IgA S1S2 titres (n = 182, r_s = -0.08, p = 0.27). KTR Kidney transplant recipients, HD hemodialysis