Table 1 Relationship between IgG anti-RBD (receptor binding domain) and anti-N (nucleocapsid) MFI (median fluorescence intensity) levels among cord blood samples with detectable SARS-CoV-2 IgA and/or IgM
Overall total tested for IgM/A N = 1038 | IgG anti-RBD MFI < 700 | IgG anti-RBD MFI⩾700 | |||||
---|---|---|---|---|---|---|---|
IgG anti-N MFI | Total tested for IgM/A N = 59 | IgG anti-N MFI | Total tested for IgM/A N = 979 | ||||
300–699 N = 18 | ⩾700 N = 41 | 300–699 N = 182 | ⩾700 N = 797 | ||||
Number with detectable IgM/A | 298 | 4 | 2 | 6 | 51 | 241 | 292 |
Proportion with detectable IgM/A [95% CI] | 0.287 [0.260, 0.316] | 0.222 [0.064, 0.476] | 0.049 [0.006, 0.165] | 0.102 [0.038, 0.208] | 0.280 [0.216, 0.351] | 0.302 [0.271, 0.335] | 0.298 [0.270, 0.327] |
Isotypes | |||||||
IgM+ n (%) | 31 (10.4) | 1 (25.0) | 1 (50.0) | 2 (33.3) | 10 (19.6) | 19 (7.9) | 29 (9.9) |
IgM+ IgA+ n (%) | 40 (13.4) | 1 (25.0) | 1 (50.0) | 2 (33.3) | 8 (15.7) | 30 (12.4) | 38 (13.0) |
IgA+ n (%) | 224 (75.2) | 2 (50.0) | 0 | 2 (33.3) | 33 (64.7) | 189 (78.4) | 222 (76.0) |
IgA+ IgM unk n (%) | 3 (1.0) | 0 | 0 | 0 | 0 | 3 (1.3) | 3 (1.0) |
P-value | 0.0003c | 0.0639a | 0.5908b |