Determinants of SARS-CoV-2 waning immunity in allogeneic hematopoietic stem cell transplant recipients

Table 1 Patient characteristics according to the obtainment of IgG(S-RBD) neutralizing level at 6 months

	IgG(S-RBD) titer at 6 months		p value
	< 1000 AU/mL (n = 37)	> 1000 AU/mL (n = 96)	p value
Male sex, n (%)	23 (62)	50 (52)	0.335
Recipient age at HSCT (years), mean ± SD	59 ± 11	57 ± 14	0.561
Donor age at HSCT (years), mean ± SD	38 ± 13	38 ± 14	0.769
Disease type, n (%)			0.906
Myeloid malignancy	28 (76)	73 (76)
Lymphoid malignancy	9 (23)	21 (22)
Non-malignant	0	2 (2)
Donor type, n (%)			0.635
HLA-identical sibling	11 (30)	37 (38.5)
Matched unrelated	21 (57)	47 (49)
Haplo-identical	5 (13)	12 (12.5)
History of GVHD requiring systemic treatment, n (%)	21 (57)	46 (48)	0.44
Disease relapse after HSCT, n (%)	5 (13.5)	16 (17)	0.794
Rituximab given within the 6 months before initiation of vaccination, n (%)	6 (16)	0 (0)	0.000339
Systemic immunosuppression (other than rituximab) given within 3 months before initiation of vaccination^a, n (%)	18 (49)	23 (24)	0.0111
Time between HSCT and initiation of vaccination, n (%)			0.24
≤ 12 months	11 (30)	18 (19)
> 12 months	26 (70)	81 (78)
Mean cell counts over study period in PB^b, n (%)
Lymphocytes, n (%)			0.00576
< 1 G/L	9 (24)	6 (6)
≥ 1 G/L	28 (76)	90 (94)
T cells, n (%)			0.144
< 1 G/L	10 (27)	15 (16)
≥ 1 G/L	27 (73)	81 (84)
B cells, n (%)			0.000643
< 0.25 G/L	20 (54)	21 (22)
≥ 0.25 G/L	17 (46)	75 (78)
Immunoglobulin level (g/L) at initiation of vaccination, mean ± SD	9.5 ± 5.5	9.2 ± 3.0	0.618
Third vaccine dose given	22 (59)	23 (24)	0.000189

^aDrugs received within the 3 months preceding vaccination consisted of cyclosporine alone (n = 21), cyclosporine + steroids (n = 10), mycophenolate mofetil alone (n = 5) or other drug combinations (n = 12)
^bMean cell counts over study period were calculated from lymphocyte, T cell and B cell counts at time of (1) first vaccine dose (n = 133, 41 and 41, respectively), (2) second vaccine dose (n = 55, 29 and 29, respectively), (3) IgG(S-RBD) quantitation after second vaccine dose (n = 118, 85 and 85, respectively), (4) third vaccine dose (n = 40, 40 and 40, respectively) and (5) IgG(S-RBD) quantitation at 6 months (n = 132, 132 and 132, respectively). The corresponding mean ± SD counts for lymphocytes, T cells and B cells in both patient groups (< 1 Log or > 1 Log AU/mL at 6 months) were 1.8 ± 1.2 versus 2.2 ± 1.0 G/L (p = 0.0796), 1.5 ± 0.9 versus 1.7 ± 0.8 G/L (p = 0.191) and 0.3 ± 0.4 versus 0.4 ± 0.3 G/L (p = 0.0194), respectively

ISSN: 1756-8722