Table 2.
Presence and severity of symptoms reported by participants with and without influenza detected on reference test (N=605).
| Symptoms | Overall, n (%) | Influenza PCRa positive (n=87), n (%) | Influenza PCR negative (n=518), n (%) | P value | |
| Feeling feverishb | 292 (48.3) | 76 (87.4) | 216 (41.7) | <.001 | |
|
|
Mild | 119 (19.7) | 14 (16.1) | 105 (20.3) | <.001 |
|
|
Moderate | 122 (20.2) | 34 (39.1) | 88 (17) | <.001 |
|
|
Severe | 51 (8.4) | 28 (32.2) | 23 (4.4) | <.001 |
| Headache | 342 (56.5) | 63 (72.4) | 279 (53.9) | .002 | |
| Coughb | 355 (58.7) | 72 (82.8) | 283 (54.6) | <.001 | |
|
|
Mild | 168 (27.8) | 17 (19.5) | 151 (29.2) | <.001 |
|
|
Moderate | 150 (24.8) | 37 (42.5) | 113 (21.8) | <.001 |
|
|
Severe | 36 (6) | 18 (20.7) | 18 (3.5) | <.001 |
| Chills or shivering | 227 (37.5) | 68 (78.2) | 159 (30.7) | <.001 | |
| Sweats | 142 (23.5) | 43 (49.4) | 99 (19.1) | <.001 | |
| Sore, itchy, or scratchy throatb | 414 (68.4) | 57 (65.5) | 357 (68.9) | .53 | |
|
|
Mild | 174 (28.8) | 27 (31) | 147 (28.4) | .04 |
|
|
Moderate | 189 (31.2) | 18 (20.7) | 171 (33) | .04 |
|
|
Severe | 49 (8.1) | 11 (12.6) | 38 (7.3) | .04 |
| Nausea or vomiting | 72 (11.9) | 21 (24.1) | 51 (9.8) | <.001 | |
| Running or stuffy nose | 358 (59.2) | 61 (70.1) | 297 (57.3) | .04 | |
| Feeling more tired than usualb | 438 (72.4) | 74 (85.1) | 364 (70.3) | .007 | |
|
|
Mild | 105 (17.4) | 11 (12.6) | 94 (18.1) | <.001 |
|
|
Moderate | 217 (35.9) | 27 (31) | 190 (36.7) | <.001 |
|
|
Severe | 116 (19.2) | 36 (41.4) | 80 (15.4) | <.001 |
| Muscle or body achesb | 300 (49.6) | 65 (74.7) | 235 (45.4) | <.001 | |
|
|
Mild | 99 (16.4) | 4 (4.6) | 95 (18.3) | <.001 |
|
|
Moderate | 146 (24.1) | 37 (42.5) | 109 (21) | <.001 |
|
|
Severe | 55 (9.1) | 24 (27.6) | 31 (6) | <.001 |
| Increased trouble with breathing | 134 (22.1) | 27 (31) | 107 (20.7) | .047 | |
| Diarrheac | 69 (11.4) | 6 (6.9) | 63 (12.2) | .19 | |
| Rashc | 9 (1.5) | 0 (0) | 9 (1.7) | .44 | |
| Ear pain or dischargec | 54 (8.9) | 11 (12.6) | 43 (8.3) | .31 | |
aPCR: polymerase chain reaction.
bIncluded survey questions on severity for a subset of symptoms presented in this table.
cSymptoms reported for children (aged <18 years) only.