Table 3. Sensitivity and specificity of symptoms of COVID-19 in the First Few X study in the United Kingdom of Great Britain and Northern Ireland, 31 January to 9 April 2020.
| Symptom, by category | No. of COVID-19 cases with symptom/total no. of COVID-19 cases | No. of non-COVID-19 cases without symptom/total no. of non-COVID-19 cases | Sensitivity, % (95% CI) | Specificity, % (95% CI) |
|---|---|---|---|---|
| Fever | ||||
| All cases | 226/353 | 418/654 | 64.0 (58.8–69.0) | 63.9 (60.1–67.6) |
| Imported cases | 108/177 | 418/654 | 61.0 (53.4–68.2) | NA |
| Sporadic cases | 72/86 | 418/654 | 83.7 (74.2–90.8) | NA |
| Secondary cases | 46/90 | 418/654 | 51.1 (40.3–61.8) | NA |
| Age < 30 years | 30/52 | 166/279 | 57.7 (43.2–71.3) | 59.5 (53.5–65.3) |
| Age 30–59 years | 135/220 | 155/227 | 61.4 (54.6–67.8) | 68.3 (61.8–74.3) |
| Age ≥ 60 years | 61/81 | 35/41 | 75.3 (64.5–84.2) | 85.4 (70.8–94.4) |
| Cough | ||||
| All cases | 296/372 | 114/735 | 79.6 (75.1–83.6) | 15.5 (13.0–18.3) |
| Imported cases | 149/193 | 114/735 | 77.2 (70.6–82.9) | NA |
| Sporadic cases | 75/86 | 114/735 | 87.2 (78.3–93.4) | NA |
| Secondary cases | 72/93 | 114/735 | 77.4 (67.6–85.4) | NA |
| Age < 30 years | 44/58 | 62/303 | 75.9 (62.8–86.1) | 20.5 (16.1–25.4) |
| Age 30–59 years | 183/233 | 27/264 | 78.5 (72.7–83.6) | 10.2 (6.9–14.5) |
| Age ≥ 60 years | 69/81 | 6/47 | 85.2 (75.6–92.1) | 12.8 (4.8–25.7) |
| Shortness of breath | ||||
| All cases | 154/366 | 500/662 | 42.1 (37.0–47.3) | 75.5 (72.1–78.8) |
| Imported cases | 54/191 | 500/662 | 28.3 (22.0–35.2) | NA |
| Sporadic cases | 59/87 | 500/662 | 67.8 (56.9–77.4) | NA |
| Secondary cases | 41/88 | 500/662 | 46.6 (35.9–57.5) | NA |
| Age < 30 years | 20/57 | 224/277 | 35.1 (22.9–48.9) | 80.9 (75.7–85.3) |
| Age 30–59 years | 91/230 | 176/235 | 39.6 (33.2–46.2) | 74.9 (68.8–80.3) |
| Age ≥ 60 years | 43/79 | 32/45 | 54.4 (42.8–65.7) | 71.1 (55.7–83.6) |
| Sore throat | ||||
| All cases | 147/347 | 297/643 | 42.4 (37.1–47.8) | 46.2 (42.3–50.1) |
| Imported cases | 78/186 | 297/643 | 41.9 (34.8–49.4) | NA |
| Sporadic cases | 28/74 | 297/643 | 37.8 (26.8–49.9) | NA |
| Secondary cases | 41/87 | 297/643 | 47.1 (36.3–58.1) | NA |
| Age < 30 years | 27/56 | 117/269 | 48.2 (34.7–62.0) | 43.5 (37.5–49.6) |
| Age 30–59 years | 97/224 | 112/231 | 43.3 (36.7–50.1) | 48.5 (41.9–55.1) |
| Age ≥ 60 years | 23/67 | 23/42 | 34.3 (23.2–46.9) | 54.8 (38.7–70.2) |
| Fever and/or cough | ||||
| All cases | 339/373 | 61/739 | 90.9 (87.5–93.6) | 8.3 (6.4–10.5) |
| Imported cases | 175/193 | 61/739 | 90.7 (85.7–94.4) | NA |
| Sporadic cases | 82/88 | 61/739 | 93.2 (85.7–97.5) | NA |
| Secondary cases | 82/92 | 61/739 | 89.1 (80.9–94.7) | NA |
| Age < 30 years | 54/57 | 31/306 | 94.7 (85.4–98.9) | 10.1 (7.0–14.1) |
| Age 30–59 years | 211/234 | 15/266 | 90.2 (85.6–93.7) | 5.6 (3.2–9.1) |
| Age ≥ 60 years | 74/82 | 6/47 | 90.2 (81.7–95.7) | 12.8 (4.8–25.7) |
| Fever and cough | ||||
| All cases | 183/380 | 573/752 | 48.2 (43.0–53.3) | 76.2 (73.0–79.2) |
| Imported cases | 82/195 | 573/752 | 42.1 (35.0–49.3) | NA |
| Sporadic cases | 65/91 | 573/752 | 71.4 (61.0–80.4) | NA |
| Secondary cases | 36/94 | 573/752 | 38.3 (28.5–48.9) | NA |
| Age < 30 years | 20/59 | 231/310 | 33.9 (22.1–47.4) | 74.5 (69.3–79.3) |
| Age 30–59 years | 107/237 | 210/268 | 45.1 (38.7–51.7) | 78.4 (72.9–83.1) |
| Age ≥ 60 years | 56/84 | 41/47 | 66.7 (55.5–76.6) | 87.2 (74.3–95.2) |
CI: confidence interval; COVID-19: coronavirus disease 2019; NA: not applicable.
a We collected data on 380 symptomatic COVID-19 cases using the First Few X protocol and 752 contemporaneous confirmed non-COVID-19 respiratory infections. Data are missing in some categories.