Table 1. Study Participants in Targeted Testing or Population Screening for SARS-CoV-2, According to Timing.
| Variable | Targeted Testing January 31–March 15 |
Population Screening March 13–April 1 |
Targeted Testing March 16–31 |
Random-Sample Population Screening April 1–4 |
||||
|---|---|---|---|---|---|---|---|---|
| All Persons (N=1924) |
SARS-CoV-2 Positive (N=177) |
All Persons (N=10,797) |
SARS-CoV-2 Positive (N=87) |
All Persons (N=7275) |
SARS-CoV-2 Positive (N=1044) |
All Persons (N=2283) |
SARS-CoV-2 Positive (N=13) |
|
| SARS-CoV-2 positivity — no. (%) | 177 (9.2) |
— | 87 (0.8) |
— | 1044 (14.4) |
— | 13 (0.6) |
— |
| SARS-CoV-2 sequencing performed — no. (%) | — | 157 (88.7) |
— | 59 (67.8) |
— | 361 (34.6) |
— | 0 |
| Male sex — no. (%) | 835 (43.4) |
92 (52.0) |
5004 (46.3) |
46 (52.9) |
2795 (38.4) |
516 (49.4) |
864 (37.8) |
9 (69.2) |
| Mean age — yr | 40.0 | 44.4 | 38.6 | 40.8 | 40.4 | 41.3 | 45.4 | 50.5 |
| Any international travel — no. (%) | — | 115 (65.0) |
939 (8.7) |
20 (23.0) |
— | 162 (15.5) |
11 (0.5) |
0 |
| Specific country of international travel — no.* | ||||||||
| China (high-risk area) | — | 1 | 2 | 0 | — | 0 | 0 | 0 |
| Austria (high-risk area February 29) | — | 43 | 16 | 0 | — | 34 | 0 | 0 |
| Italy (high-risk area February 29) | — | 45 | 7 | 1 | — | 3 | 0 | 0 |
| Switzerland (high-risk area February 29) | — | 9 | 11 | 0 | — | 2 | 1 | 0 |
| United Kingdom | — | 7 | 193 | 12†‡ | — | 44 | 0 | 0 |
| United States | — | 7 | 160 | 3 | — | 18 | 1 | 0 |
| Denmark | — | 2 | 90 | 1 | — | 2 | 2 | 0 |
| Germany (high-risk area March 12) | — | 1 | 36 | 1 | — | 2 | 0 | 0 |
| Spain (high-risk area March 14) | — | 0 | 142 | 1‡ | — | 34 | 3 | 0 |
| The Netherlands | — | 0 | 26 | 2† | — | 5 | 1 | 0 |
| Poland | — | 0 | 45 | 1 | — | 0 | 0 | 0 |
| Other | — | 0 | 247 | 0 | — | 14 | 4 | 0 |
| Known contact with infected person — no. (%) | — | 71 (40.1) |
281 (2.6) |
6 (6.9) |
— | 629 (60.2) |
60 (2.6) |
1 (7.7) |
| Reported any symptoms — no. (%)‡ | — | 153 (86.4) |
3579 (33.1) |
51 (58.6) |
— | 985 (94.3) |
271 (11.9) |
6 (46.2) |
| Reported specific symptoms — no. | — | 78 | 3579 | 51 | — | 950 | 271 | 6 |
| Distribution of symptoms reported — no. (%) | ||||||||
| Fever | — | 38 (42.1)§ |
410 (3.8) |
17 (19.5) |
— | 491 (48.8)§ |
21 (0.9) |
0 |
| Cough | — | 23 (25.5)§ |
1769 (16.4) |
32 (36.8) |
— | 313 (31.1)§ |
87 (3.8) |
3 (23.1) |
| Body aches | — | 26 (28.8)§ |
537 (5.0) |
19 (21.8) |
— | 310 (30.8)§ |
43 (1.9) |
1 (7.7) |
| Headache | — | 21 (23.3)§ |
1,086 (10.1) |
18 (20.7) |
— | 239 (23.7)§ |
89 (3.9) |
2 (15.4) |
| Sore throat | — | 15 (16.6)§ |
1,558 (14.4) |
26 (29.9) |
— | 123 (12.2)§ |
107 (4.7) |
0 |
| Rhinorrhea | — | 14 (15.5)§ |
1,784 (16.5) |
24 (27.6) |
— | 126 (12.5)§ |
139 (6.1) |
4 (30.8) |
| Fatigue¶ | — | 12 (13.3)§ |
— | — | — | 207 (20.6)§ |
— | — |
| Loss of smell or taste‖ | — | 2 (2.2)§ |
— | — | — | 116 (11.5)§ |
13 (0.6) |
1 (7.7) |
| Other | — | 14 (15.5)§ |
911 (8.4) |
15 (17.2) |
— | 254 (25.2)§ |
88 (3.9) |
3 (23.1) |
On March 19, all travel outside Iceland was designated as high-risk.
One person traveled to the United Kingdom and the Netherlands.
One person traveled to the United Kingdom and Spain.
Information regarding symptoms was not collected for participants who tested negative in the targeted testing. Symptoms were not recorded for all the participants who were targeted for testing. Therefore, for the early targeted-testing group, we used the formula: 100(symptom count/78×[153/177]), and for the later targeted-testing group, we used the formula 100(symptom count/950×[985/1044]).
Participants were not queried about fatigue in the population screening.
Participants were not queried about loss of smell or taste in the open-invitation phase of the population screening.