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Table 2 Sensitivity of the rapid antibody test, stratified by antibody isotype

From: Low detection rate of RT-PCR-confirmed COVID-19 using IgM/IgG rapid antibody tests in a large community sample in Lima, Peru

Group

Sensitivity of the IgM/IgG antibody isotype, % (95% CI)

Sensitivity of the IgM antibody isotype, % (95% CI)

Sensitivity of the IgG antibody isotype, % (95% CI)

IgM vs. IgG isotype, p–value

Full sample (n = 492)

46.7 (42.4, 51.2)

36.6 (32.5, 40.9)

36.4 (32.3, 40.7)

1.0

Presence of reported symptoms

 Yes (n = 372)

44.6 (39.7, 49.7)

36.3 (31.6, 41.3)

34.4 (29.8, 39.4)

0.65

 No (n = 120)

53.3 (44.4, 62.0)

37.5 (29.4, 46.4)

42.5 (34.0, 51.4)

0.51

 Yes vs. no, p–value

0.12

0.90

0.14

n/a

Time since onset of earliest symptom, among those reporting symptoms (N = 372)

 Week 1 (n = 224)

30.4 (24.7, 36.6)

24.1 (19.0, 30.1)

18.8 (14.2–24.4)

0.21

 Week 2 (n = 106)

62.3 (52.7, 70.9)

52.8 (43.4, 62.1)

53.8 (44.3–63.0)

1.0

 Week 3 (n = 31)

77.4 (59.8, 88.8)

58.1 (40.7, 73.5)

74.2 (56.5–86.4)

0.28

 Week 4 (n = 6)

83.3 (41.6, 98.4)

83.3 (41.6, 98.4)

50.0 (19.0–81.0)

0.54

 Week 5+ (n = 5)

60.0 (23.1, 88.0)

40.0 (12.0–76.9)

60.0 (23.1–88.0)

1.0

 Comparing time intervals, p–value

< 0.01

< 0.01

< 0.01

n/a

  1. IgM/IgG antibody test positivity included those who had either or both IgM and IgG band; IgM antibody test positivity included those who had at least an IgM band; IgG antibody test positivity included those who had at least an IgG band. The p-values were estimated using Pearson’s chi-squared test