Table 1.

Multiple Influenza Challenge Exposure Timing and Outcomes

Participant (Sex, Age, y)	Challenge Date	Viral Dose (TCID50)	Nasal Viral Detection (Duration, d)	Days of Symptoms	No. of Symptoms	Severity Scorea	D0 and W8 HAI Titerb	D0 and W8 NAI Titerb	D0 and W8 HA Stalk Titerb	PBL Gene Expressionc
Challenge 1
1 (F, 21)	9 Oct 2012	106	+ (4)	5	11	55	0–40	0–1280	44 084–80 480	+
2 (M, 19)	25 Sept 2012	106	– (0)	6	1	6	10–10	1280–2560	NA	–
3 (M, 24)	21 Jan 2013	107	+ (1)	8	6	48	20–160	160–2560	43 048–58 892	+
4 (M, 21)	19 Mar 2013	107	– (0)	2	1	2	0–160	2560–1280	65 165–81 987	+
5 (F, 24)	2 Apr 2013	107	+ (7)	11	12	132	0–40	0–80	27 422–86 008	+
6 (F, 24)	10 Dec 2012	106	– (0)	6	2	12	0–80	80–160	NA	–
7 (F, 28)	5 Jun 2012	103	– (0)	1	2	2	0–10	0–40	NA	NA
Challenge 2
1 (F, 22)	15 Oct 2013	107	+ (2)	0	0	0	10–80	80–640	60 221–83 250	+
2 (M, 21)	15 Oct 2013	107	+ (1)	0	0	0	0–80	640–2560	42 016–96 331	–
3 (M, 24)	12 Nov 2013	107	+ (1)	11	5	55	160–160	1280–1280	86 034–67 954	+
4 (M, 21)	12 Nov 2013	107	– (0)	4	3	12	10–20	1280–1280	NA	–
5 (F, 24)	12 Nov 2013	107	– (0)	4	5	20	20–80	320–320	54 703–55 000	–
6 (F, 25)	12 Nov 2013	107	– (0)	5	3	15	40–160	80–80	24 681–22 228	–
7 (F, 30)	9 Dec 2013	107	+ (6)	7	8	56	0–10	0–320	18 486–60 623	NA

Abbreviations: –, negative; +, positive; D0, prechallenge baseline day 0; F, female; HA, hemagglutinin; HAI, hemagglutination inhibition; M, male; NA, not available for testing; NAI, neuraminidase inhibition; PBL, peripheral blood leukocyte; TCID₅₀, 50% tissue culture infectious dose; W8, 8 weeks after challenge.

^aMean and median symptom scores across both challenge trials were 35.5 and 10, respectively. Severity scores ranged from 0 to 750. Symptom scores represent the totality of the disease experienced after challenge.

^bSerum antibody titers against the hemagglutinin head, NAI, and HA stalk were measured at D0 and at W8.

^cPeripheral blood leukocyte expression of antiviral and immune-related genes is shown in Figure 1.