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Table 2 Diagnostic accuracy parameters for the saliva and nasal Ag-RDTs. Values are percentages (95% confidence interval) unless stated otherwise

From: Head-to-head comparison of the accuracy of saliva and nasal rapid antigen SARS-CoV-2 self-testing: cross-sectional study

Analysis

No

Prevalencea [%]

Sensitivity [%]

(95%CI)

Specificity [%]

(95%CI)

PPV [%]

(95%CI)

NPV [%]

(95%CI)

COVID-19 antigen rapid test (oral fluid) for self-testing (Hangzhou AllTest Biotech Co., Ltd.)

Primary analysis

2803

6.5

46.7 (39.3 to 54.2)

99.0 (98.5 to 99.4)

76.6 (67.6 to 84.1)

96.4 (95.6 to 97.1)

Secondary (stratified) analysis

 Infectiousness viral load cut-offb,$

2788

5.1

54.9 (46.4 to 63.3)

98.8 (98.3 to 99.2)

70.9 (61.5 to 79.2)

97.6 (97.0 to 98.2)

 Symptoms present at samplingc

  Yes

2306

6.5

51.0 (42.7 to 59.2)

98.8 (98.3 to 99.2)

75.5 (66.0 to 83.5)

96.6 (95.8 to 97.4)

  No

484

6.4

25.8 (11.9 to 44.6)

99.8 (98.8 to 100)

88.9 (51.8 to 99.7)

95.2 (92.8 to 96.9)

 Vaccinated (at least one)d

  Yes

2390

4.8

47.0 (37.6 to 56.5)

99.0 (98.5 to 99.4)

71.1 (59.5 to 80.9)

97.4 (96.6 to 98.0)

  No

404

16.6

46.3 (34.0 to 58.9)

98.8 (97.0 to 99.7)

88.6 (73.3 to 96.8)

90.2 (86.7 to 93.1)

 Previous SARS-CoV-2 infectione

  Yes

366

5.5

20.0 (5.7 to 43.7)

99.1 (97.5 to 99.8)

57.1 (18.4 to 90.1)

95.5 (92.9 to 97.4)

  No

2427

6.7

50.0 (42.1 to 57.9)

99.0 (98.5 to 99.4)

77.9 (68.7 to 85.4)

96.5 (95.7 to 97.2)

 Sexf

  Female

1711

6.3

38.0 (28.8 to 47.8)

99.2 (98.6 to 99.6)

75.9 (62.4 to 86.5)

96.0 (94.9 to 96.9)

  Male

1081

6.8

60.3 (48.1 to 71.5)

98.7 (97.8 to 99.3)

77.2 (64.2 to 87.3)

97.2 (96.0 to 98.1)

 Age [years]g

  ≥ 16 to ≤ 40

1450

6.3

41.3 (31.1 to 52.1)

98.9 (98.2 to 99.4)

71.7 (57.7 to 83.2)

96.1 (95.0 to 97.1)

  > 40 to ≤ 65

1135

6.3

50.0 (38.0 to 62.0)

99.2 (98.4 to 99.6)

80.0 (65.4 to 90.4)

96.7 (95.5 to 97.7)

  > 65

208

8.2

64.7 (38.3 to 85.8)

99.0 (96.3 to 99.9)

84.6 (54.6 to 98.1)

96.9 (93.4 to 98.9)

SD Biosensor SARS-CoV-2 Rapid Antigen Test Nasal by Roche Diagnostics (‘Nasal’),

Primary analysis

2819

6.4

68.9 (61.6 to 75.6)

99.5 (99.2 to 99.8)

91.2 (85.1 to 95.4)

97.9 (97.3 to 98.4)

Secondary (stratified) analysis

 Infectiousness viral load cut-offb,$

2804

5.1

83.9 (76.9 to 89.5)

99.5 (99.2 to 99.7)

90.2 (83.9 to 94.7)

99.1 (98.7 to 99.5)

 Symptoms present at samplingc

  Yes

2319

6.4

78.5 (71.1 to 84.8)

99.5 (99.2 to 99.8)

92.1 (86.0 to 96.2)

98.5 (97.9 to 99.0)

  No

487

6.4

22.6 (9.6 to 41.1)

99.6 (98.4 to 99.9)

77.8 (40.0 to 97.2)

95.0 (92.6 to 96.8)

 Vaccinated (at least one)d

  Yes

2389

4.5

70.1 (60.5 to 78.6)

99.6 (99.2 to 99.8)

88.2 (79.4 to 94.2)

98.6 (98.0 to 99.0)

  No

421

17.3

67.1 (55.1 to 77.7)

99.4 (97.9 to 99.9)

96.1 (86.5 to 99.5)

93.5 (90.5 to 95.8)

 Previous SARS-CoV-2 infectione

  Yes

372

5.1

36.8 (16.3 to 61.6)

99.2 (97.5 to 99.8)

70.0 (34.8 to 93.3)

96.7 (94.3 to 98.3)

  No

2437

6.6

72.7 (65.1 to 79.4)

99.6 (99.3 to 99.8)

92.9 (86.9 to 96.7)

98.1 (97.5 to 98.6)

 Sexf

  Female

1717

6.2

68.9 (59.1 to 77.5)

99.6 (99.1 to 99.8)

91.2 (82.8 to 96.4)

98.0 (97.2 to 98.6)

  Male

1090

6.7

69.9 (58.0 to 80.1)

99.5 (98.9 to 99.8)

91.1 (80.4 to 97.0)

97.9 (96.8 to 98.7)

 Age [years]g

  16 to ≤ 40

1463

6.4

66.7 (56.1 to 76.1)

99.5 (99.0 to 99.8)

89.9 (80.2 to 95.8)

97.8 (96.9 to 98.5)

  > 40 to ≤ 65

1139

6.1

72.9 (60.9 to 82.8)

99.6 (99.0 to 99.9)

92.7 (82.4 to 98.0)

98.2 (97.3 to 98.9)

  > 65

206

7.8

68.8 (41.3 to 89.0)

99.5 (97.1 to 100)

91.7 (61.5 to 99.8)

97.4 (94.1 to 99.2)

  1. PPV positive predictive value, NPV negative predictive value
  2. aSARS-CoV-2 infection based on molecular test result
  3. bViral load cut-off for infectiousness, defined as viral load above which 95% of people with a positive RT-PCR test result had a positive viral culture6, was 5.2 log10 SARS-CoV-2 E-gene copies/mL
  4. cSymptoms not available for 13, and 13 participants, including 0, and 0 with a positive molecular test result, in those that had a saliva test result, and those that had a nasal test result, respectively
  5. dCOVID-19 vaccination status not available from 9, and 9 participants, including 0, and 0 with a positive molecular test result in those with a saliva test result and nasal test result, respectively
  6. ePrevious SARS-CoV-2 infection information not available from 10 and 10 participants, including 0 and 0 with a positive molecular test result, in those that had a saliva test result and those that had a nasal test result, respectively
  7. fSex not available from 11 and 12 participants that had a saliva test result and that had a nasal test result, respectively
  8. gAge was not available from 10 and 11 participants that had a saliva test result and that had a nasal test result, respectively
  9. $Viral load unavailable for 15 individuals that had a saliva test result and 15 individuals that had a nasal test result