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Table 1 Baseline characteristics of the study population, stratified by type of Ag-RDT

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

Test result available from the reference test and…

Saliva Ag-RDT

Nasal Ag-RDT

Sample size

N = 2803

N = 2819

Age [years], mean (SD)a

40.9 (15.5)

40.8 (15.5)

Sex, female, n (%)b

1711 (61.3)

1717 (61.1)

Highest level of education, n (%)c

 Primary

49 (1.7)

48 (1.7)

 Secondary

1329 (47.4)

1332 (47.3)

 College/University, Bachelor’s degree

974 (34.7)

988 (35.0)

 College/University, Master’s degree

418 (14.9)

416 (14.8)

Vaccination statusd

 Not vaccinated

404 (14.4)

421 (14.9)

 No information on vaccination status

9 (0.3)

9 (0.3)

 Vaccinated with at least one dose, n (%)

2390 (85.3)

2389 (84.7)

  Type of vaccine, n (%)e

     Astra Zeneca

292 (10.4)

291 (10.3)

     Janssen

151 (5.4)

152 (5.4)

     Moderna

270 (9.6)

270 (9.6)

     Pfizer

1663 (59.3)

1663 (59.0)

     Unknown

14 (0.5)

13 (0.5)

  Number of vaccinations received, n (%)e

     1

308 (11.0)

305 (10.8)

     2

2081 (74.2)

2083 (73.9)

     Unknown

1 (0.0)

1 (0.0)

At least one prior SARS-CoV-2 infection, n (%)f

366 (13.1)

372 (13.2)

 Less than 2 months ago

24 (6.6)

24 (6.5)

 2 to 6 months ago

99 (27.0)

100 (26.9)

 6 to 12 months ago

209 (57.1)

214 (57.5)

 More than 12 months ago

34 (9.3)

34 (9.1)

 Testing information, n (%)!

 Asymptomatic—close contact of confirmed SARS-CoV-2 infected household member

113 (4.1)

115 (4.1)

 Asymptomatic—close contact of other confirmed SARS-CoV-2 infected individual

138 (4.9)

136 (4.8)

 Asymptomatic—other

233 (8.4)

236 (8.4)

 Symptoms at time of sampling, n (%)g

2306 (82.7)

2319 (82.6)

    Symptom onset, n (%)h

     On day of sampling

185 (8.0)

187 (8.0)

     A day before sampling

931 (40.1)

932 (40.0)

     Two days before sampling

672 (29.0)

684 (29.3)

     Three or more days before sampling

518 (22.3)

516 (22.1)

     Unknown

13 (0.6)

13 (0.6)

    Type of symptoms (self-reported), n (%)h,i

     Common cold

2111 (91.0)

2118 (90.8)

     Shortness of breath

388 (16.7)

391 (16.8)

     Fever

417 (18.0)

417 (17.9)

     Coughing

1254 (54.1)

1253 (53.7)

     Loss of taste or smell

113 (4.9)

109 (4.7)

     Muscle ache

245 (10.6)

247 (10.6)

     Other symptoms

196 (8.5)

202 (8.7)

  1. In the Netherlands, individuals are notified of a close contact by the Dutch public health service test-and-trace program and/or the Dutch contact tracing mobile phone application (the CoronaMelder app) and/or an individual with a confirmed SARS-CoV-2 infection (index case)
  2. Out of the total group of participants, 2746 had a test result available for both tests
  3. SD standard deviation
  4. aAge was not available from 10 and 11 participants that had a saliva test result and that had a nasal test result, respectively
  5. bSex not available from 11 and 12 participants that had a saliva test result and that had a nasal test result, respectively
  6. cLevel of education was not available from 33 and 35 participants that had a saliva test result and that had a nasal test result, respectively
  7. 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
  8. ePercentage calculated as proportion of those vaccinated
  9. fPrevious 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
  10. gSymptoms 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
  11. hPercentage calculated as proportion of those with symptoms at time of sampling
  12. iTotals add up to a number higher than the number of individuals with symptoms at the time of sampling because individuals could report more than one symptom
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BMC Medicine

ISSN: 1741-7015

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