Table 1.
Baseline characteristics of the study population, stratified by type of Ag-RDT
| 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) |
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)
Out of the total group of participants, 2746 had a test result available for both tests
SD standard deviation
aAge was not available from 10 and 11 participants that had a saliva test result and that had a nasal test result, respectively
bSex not available from 11 and 12 participants that had a saliva test result and that had a nasal test result, respectively
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
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
ePercentage calculated as proportion of those vaccinated
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
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
hPercentage calculated as proportion of those with symptoms at time of sampling
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