TABLE 2.

Symptom presence, symptom onset, and impact on activities in participants with and without lab-confirmed influenza

	Overall (976)	Influenza negative (774)	Influenza positive (202)	P
New or worsening:	N (%)
Fever	441 (45.2)	304 (39.3)	137 (67.8)	<0.001
Headache	672 (68.9)	522 (67.4)	150 (74.3)	0.075
Cough	789 (80.8)	610 (78.8)	179 (88.6)	0.002
Chills/shivering	402 (41.2)	270 (34.9)	132 (65.3)	<0.001
Sweats	352 (36.1)	250 (32.3)	102 (50.5)	<0.001
Sore throat	725 (74.3)	569 (73.5)	156 (77.2)	0.325
Vomiting	153 (15.7)	111 (14.3)	42 (20.8)	0.033
Runny nose	741 (75.9)	581 (75.1)	160 (79.2)	0.257
Sneezing	577 (59.1)	466 (60.2)	111 (55.0)	0.203
Fatigue	784 (80.3)	617 (79.7)	167 (82.7)	0.40
Muscle or body aches	597 (61.2)	447 (57.8)	150 (74.3)	<0.001
Trouble breathing	313 (32.1)	235 (30.4)	78 (38.6)	0.031
No symptoms	38 (3.9)	34 (4.4)	4 (2.0)	0.169
Illness felt worse than a typical cold	569 (58.3)	410 (53)	159 (78.7)	<0.001
Participant perceived illness as:				<0.001
Cold	524 (53.7)	459 (59.3)	65 (32.2)
Flu	314 (32.2)	190 (24.5)	124 (61.4)
Other	138 (14.1)	125 (16.1)	13 (6.4)
Symptom onset within:				0.044
0.5 days	0 (0.0)	0 (0.0)	0 (0.0)
1 day	372 (38.1)	289 (37.3)	83 (41.1)
1.5 days	161 (16.5)	122 (15.8)	39 (19.3)
2 days	96 (9.8)	85 (11.0)	11 (5.4)
3 days	49 (5.0)	44 (5.7)	5 (2.5)
4 days	10 (1.0)	8 (1.0)	2 (1.0)
5 days	19 (1.9)	17 (2.2)	2 (1.0)
No answer	269 (27.6)	209 (27.0)	60 (29.7)
Activities impacted by illness:				<0.001
Not at all	85 (8.7)	78 (10.1)	7 (3.5)
A little bit	334 (34.2)	294 (38.0)	40 (19.8)
Somewhat	282 (28.9)	234 (30.2)	48 (23.8)
Quite a bit	183 (18.8)	121 (15.6)	62 (30.7)
Very much	92 (9.4)	47 (6.1)	45 (22.3)