Table 3.
Summary characteristics of Antibodies to Nucleocapsid protein (anti-N) during first re-infection events occurring during the observation window (n = 118 of n = 129 re-infection events overall), by identification method, vs. a randomly selected interview following incident infection and without evidence of re-infection (n = 200)
| Random interview without evidence of re-infection (N = 200) | First re-infection event | |||
|---|---|---|---|---|
| Identified through longitudinal serology only ( N = 90) | Identified through testing ( N = 28) | |||
| Anti-N RR a in previous interview | Mean (SD) RR | 1.06 (1.08) | 0.70 (0.74) | 0.64 (0.85) |
| Median (IQR) RR | 0.64 (0.39–1.57) | 0.40 (0.24–0.84) | 0.45 (0.13–0.69) | |
| Anti-N RR a during interview | Mean (SD) RR | 0.9 (0.92) | 2.32* (1.39) | 1.81 (1.61) |
| Median (IQR) RR | 0.56 (0.3–1.17) | 2.31* (0.94–3.49*) | 1.23 (0.40–3.31*) | |
| Difference b in anti-N RR a between interviews | Mean (SD) RR | -0.19 (0.88) | 1.62 (1.21) | 1.16 (1.60) |
| Median (IQR) RR | -0.14 (-0.44–0.03) | 1.29 (0.48–2.79*) | 0.58 (-0.08–2.67*) | |
| Ratio c in anti-N RR a between interviews | Mean (SD) RR | 1.45 (3.74) | 6.21 (6.89) | 5.93 (8.19) |
| Median (IQR) RR | 0.79 (0.57–1.12) | 3.64 (1.99–7.18) | 3.17 (0.86–6.62) | |
| Days between infections | Mean (SD) | N/A | 322.82 (147.50) | 360.97 (142.10) |
| Median (IQR) | N/A | 315.94 (209.40–414.00) | 338.57 (280.30–448.00) | |
Anti-N = Antibodies to Nucleocapsid protein; RR = Relative Ratio; IQR = Interquartile Range
aAnti-N relative ratios are derived from the blood sample (plasma or dried blood spot) ELISA, primary dilution (1:160 (0.0625µL/well) only
bDifference in anti-N RR represents [anti-N RR at selected interview– anti-N RR at immediately preceding interview]
cRatio in anti-N RR represents [anti-N RR at selected interview / anti-N RR at immediately preceding interview]
*Value is outline of the linear range of the assay: results are thus likely an underestimate of true levels