Immunogenicity and safety of cell-derived MF59®-adjuvanted A/H1N1 influenza vaccine for children

Figures & data

Table 1. Demographics and other baseline characteristics of subjects in cohorts 1, 2, 3 and 4 (enrolled population, excluding non-compliant site)

	Cohort 1 (9–17 years)			Cohort 2 (3–8 years)
	3.75 μg +halfMF59 (n = 80 )	7.5 μg +fullMF59 (n = 79 )	Total (n = 159 )	3.75 μg +halfMF59 (n = 72 )	7.5 μg +fullMF59 (n = 73 )	15 μg +noMF59 (n = 39 )	Total (n = 184 )
Age (years), mean ± SD	13.2±2.7	13.2±2.7	13.2±2.7	5.5±1.9	5.3±1.7	5.2±1.5	5.3±1.7
Age (months), mean ± SD	166.9±32.7	167.5±31.4	167.2±32.0	71.6±24.7	69.6±21.6	68.4±20.1	70.1±22.5
Sex, n (%)
Male	39 (49)	42 (53)	81 (51)	27 (38)	42 (58)	14 (36)	83 (45)
Female	41 (51)	37 (47)	78 (49)	45 (63)	31 (42)	25 (64)	101 (55)
Ethnic origin, n (%)
Asian	2 (3)	0	2 (1)	0	1 (1)	1 (3)	2 (1)
Black	0	0	0	3 (4)	2 (3)	0	5 (3)
Caucasian	77 (96)	79 (100)	156 (98)	64 (89)	70 (96)	34 (87)	168 (91)
Hispanic	0	0	0	2 (3)	0	0	2 (1)
Other	1 (1)	0	1 (<1)	3 (4)	0	4 (10)	7 (4)
Height (cm), mean ± SD	158.8±16.0	159.8±15.6	159.3±15.7	116.8±13.5	114.8±11.5	113.0±11.4	115.2±12.3
Weight (kg), mean ± SD	51.4±15.7	52.5±16.2	51.9±15.9	22.1±6.5	21.6±5.3	21.1±5.9	21.7±5.9
Body mass index (kg/m^2), mean ± SD	19.9±3.3	20.2±4.6	20.0±4.0	16.0±3.0	16.1±1.7	16.2±2.1	16.1±2.4
Previous influenza vaccination, n (%)	14 (18)	22 (28)	36 (23)	18 (25)	16 (22)	8 (21)	42 (23)
	Cohort 3 (1–<3 years)				Cohort 4 (6–11 months)
	3.75 μg +halfMF59 (n = 66 )	7.5 μg +fullMF59 (n = 71 )	15 μg +noMF59 (n = 35 )	Total (n = 172 )	3.75 μg +halfMF59 (n = 75 )	7.5 μg +fullMF59 (n = 76 )	Total (n = 151)
Age (months), mean ± SD	21.8±7.3	23.1±7.1	23.1±7.8	22.6±7.3	8.9±1.5	8.8 ±1.7	8.9±1.6
Sex, n (%)
Male	32 (48)	46 (65)	20 (57)	98 (57)	35 (47)	34 (45)	69 (46)
Female	34 (52)	25 (35)	15 (43)	74 (43)	40 (53)	42 (55)	82 (54)
Ethnic origin, n (%)
Asian	2 (3)	2 (3)	2 (6)	6 (3)	0	0	0
Black	2 (3)	1 (1)	1 (3)	4 (2)	0	3 (4)	3 (2)
Caucasian	37 (56)	42 (59)	19 (54)	98 (57)	12 (16)	10 (13)	22 (15)
Hispanic	24 (36)	25 (35)	13 (37)	62 (36)	63 (84)	62 (82)	125 (83)
Other	1 (2)	1 (1)	0	2 (1)	0	1 (1)	1 (<1 )
Height (cm), mean ± SD	83.9±7.0	85.7±7.8	85.0±7.2	84.9±7.4	71.4±4.8	71.4±4.0	71.4±4.4
Weight (kg), mean ± SD	12.5±2.4	13.0±2.6	12.0±2.1	12.6±2.4	9.1±1.3	9.1±1.4	9.1±1.4
Body mass index (kg/m^2), mean ± SD	17.7±2.6	17.8±3.1	16.7±2.2	17.5±2.7	18.0±2.4	17.9±2.5	17.9±2.4
Previous influenza vaccination, n (%)	5 (8)	5 (7)	3 (9)	13 (8)	0	0	0

SD, standard deviation

Figure 1. Subject disposition in each age cohort and vaccine group. *N values include blood draws outside the specified time window; ^†Fourth vaccination to be done only on the subset of naïve subjects <9 years of age. HI – hemagglutination inhibition.

Table 2. Geometric mean titers (GMT) and geometric mean ratios (GMR) – hemagglutination inhibition assay, per-protocol set*

	Cohort 1 (9–17 years)		Cohort 2 (3–8 years)			Cohort 3 (1–<3 years)			Cohort 4 (6–11 months)
	3.75 μg +halfMF59 (n = 72 )	7.5 μg +fullMF59 (n = 71 )	3.75 μg +halfMF59 (n = 58 )	7.5 μg +fullMF59 (n = 60 )	15 μg +noMF59 (n = 31 )	3.75 μg +halfMF59 (n = 51 )	7.5 μg +fullMF59 (n = 53 )	15 μg +noMF59 (n = 25 )	3.75 μg +halfMF59 (n = 58 )	7.5 μg +fullMF59 (n = 54 )
GMT day 1	6.72 (5.58–8.1)	5.86 (4.89–7.01)	5.65 (5.1–6.26)	5.39 (4.9–5.94)	5.38 (4.75–6.08)	7.33 (4.08–13)	8.52 (5.01–14)	12 (5.79–23)	8.35 (3.37–21)	8.33 (3.35–21)
GMT day 22	90 (61–131)	140 (97–203)	61 (41–90)	73 (50–107)	35 (21–56)	43 (21–91)	63 (32–123)	22 (9.26–54)	43 (13–148)	82 (24–282)
GMR day 22/day 1	13 (9.09–20)	24 (17–35)	11 (7.29–16)	14 (9.46–20)	7 (4.07–10)	6 (3.53–9.97)	7 (4.6–12)	2 (1.04–3.56)	5 (2.63–10)	10 (5.01–20)
GMT day 43	314 (254–387)	466 (380–572)	487 (379–626)	622 (492–788)	151 (112–204)	650 (419–1009)	917 (616–1366)	131 (77–221)	770 (431–1376)	1074 (600–1921)
GMR day 43/day 1	47 (36–61)	80 (61–103)	86 (67–111)	115 (91–147)	28 (21–38)	89 (54–145)	108 (69–169)	11 (6.23–20)	92 (51–166)	129 (72–232)
Pre-booster	n = 21	n = 22	n = 24	n = 31	n = 11	n = 36	n = 41	n = 19	n = 52	n = 46
GMT day 366	99 (49–198)	150 (78–286)	162 (106–248)	171 (118–248)	89 (52–151)	154 (81–295)	235 (130–425)	56 (26–119)	142 (76–267)	254 (129–501)
GMR day 366/day 1	17 (8.33–33)	25 (13–47)	28 (18–44)	29 (20–43)	17 (9.58–29)	23 (12–46)	32 (17–60)	5 (2.22–11)	18 (8.78–37)	33 (15–72)
Post-booster	n = 19	n = 20	n = 20	n = 29	n = 10	n = 32	n = 38	n = 17	n = 47	n = 40
GMT day 387	1701 (1114–2599)	1339 (934–1918)	4577 (2815–7443)	4496 (2982–6776)	2618 (1439–4764)	3389 (2021–5684)	3783 (2371–6034)	1852 (1007–3407)	5076 (3436–7499)	5994 (3920–9165)
GMR day 387/day 1	319 (198–515)	226 (151–340)	777 (448–1349)	760 (477–1211)	496 (251–977)	478 (200–1144)	548 (249–1205)	151 (54–424)	621 (215–1790)	712 (225–2253)
GMR day 387/366	15 (6.89–33)	8.47 (4.34–17)	28 (15–51)	26 (16–43)	30 (14–62)	19 (9.73–39)	17 (8.88–31)	36 (16–81)	33 (17–63)	23 (11–46)

*Data presented for days 1–366 are derived from a re-analysis of the original dataset following protocol violation regarding the administration of the booster. This violation required the retrospective removal of the non-compliant site data from the original data set. Data presented for the booster correspond to the original dataset as the non-compliant site did not contribute post-booster data.

Figure 2. Reverse cumulative distribution of hemagglutination inhibition (HI) titers in cohort 1 (A), cohort 2 (B), cohort 3 (C) and cohort 4 (D) on days 1, 22 and 43.

Table 3. Number (percentage and 95% confidence interval) of subjects with hemagglutination inhibition titer ≥1:40 (per-protocol set)*

	Cohort 1 (9–17 years)		Cohort 2 (3–8 years)			Cohort 3 (1–<3 years)			Cohort 4 (6–11 months)
	3.75 μg +halfMF59 (n = 72 )	7.5 μg +fullMF59 (n = 71 )	3.75 μg +halfMF59 (n = 58 )	7.5 μg +fullMF59 (n = 60 )	15 μg +noMF59 (n = 31 )	3.75 μg +halfMF59 (n = 51 )	7.5 μg +fullMF59 (n = 53 )	15 μg +noMF59 (n = 25 )	3.75 μg +halfMF59 (n = 58 )	7.5 μg +fullMF59 (n = 54 )
Day 1	4 (6) (2–14)	2 (3) (0–10)	0 (0) (0–6)	1 (2) (0.042–9)	0 (0) (0–11)	6 (12) (4–24)	7 (13) (5–25)	5 (20) (7–41)	10 (17) (9–29)	9 (17) (8–29)
Day 22	59 (82)^† (71–90)	64 (90)^† (81–96)	46 (79)^† (67–89)	50 (83)^† (71–92)	20 (65) (45–81)	37 (73)^† (58–84)	41 (77)^† (64–88)	8 (32) (15–54)	33 (57) (43–70)	40 (74)^† (60–85)
Day 43	72 (100)^† (95–100)	71 (100)^† (95–100)	58 (100)^† (94–100)	60 (100)^† (94–100)	30 (97)^† (83–100)	51 (100)^† (93–100)	53 (100)^† (93–100)	22 (88)^† (69–97)	58 (100)^† (94–100)	54 (100)^† (93–100)
Pre-booster	n = 21	n = 22	n = 24	n = 31	n = 11	n = 36	n = 41	n = 19	n=52	n = 46
Day 366	18 (86)^† (64–97)	21 (95)^† (77–100)	24 (100)^† (86–100)	31 (100)^† (89–100)	10 (91)^† (59–100)	36 (100)^† (90–100)	41 (100)^† (91–100)	14 (74)^† (49–91)	49 (94)^† (84–99)	46 (100)^† (92–100)
Post-booster	n = 19	n = 20	n = 20	n = 29	n = 10	n = 32	n = 38	n = 17	n = 47	n = 40
Day 387	19 (100)^† (82–100)	20 (100)^† (83–100)	20 (100)^† (83–100)	29 (100)^† (88–100)	10 (100)^† (69–100)	32 (100)^† (89–100)	38 (100)^† (91–100)	17 (100)^† (80–100)	47 (100)^† (92–100)	40 (100)^† (91–100)

*Data presented for days 1–366 are derived from a re-analysis of the original data set following protocol violation regarding the administration of the booster. This violation required the retrospective removal of the non-compliant site data from the original dataset. Data presented for the booster correspond to the original data set as the non-compliant site did not contribute post-booster data. ^†Percentage of subjects achieving hemagglutination inhibition titer ≥1:40 is >70%.

Table 4. Number (percentage and 95% confidence interval) of subjects who achieved seroconversion or significant increase in hemagglutination inhibition (per-protocol set)*

	Cohort 1 (9–17 years)		Cohort 2 (3–8 years)			Cohort 3 (1–<3 years)			Cohort 4 (6–11 months)
	3.75 μg +halfMF59 (n = 72 )	7.5 μg +fullMF59 (n = 71 )	3.75 μg+halfMF59 (n = 58 )	7.5 μg +fullMF59 (n = 60 )	15 μg +noMF59 (n = 31 )	3.75 μg +halfMF59 (n = 51 )	7.5 μg +fullMF59 (n = 53 )	15 μg +noMF59 (n = 25 )	3.75 μg +halfMF59 (n = 58 )	7.5 μg +fullMF59 (n = 54 )
Day 22	56 (78)^† (66–87)	63 (89)^† (79–95)	46 (79)^† (67–89)	50 (83)^† (71–92)	20 (65)^† (45–81)	37 (73)^† (58–84)	41 (77)^† (64–88)	8 (32) (15–54)	33 (57)^† (43–70)	40 (74)^† (60–85)
Day 43	71 (99)^† (93–100)	71 (100)^† (95–100)	58 (100)^† (94–100)	60 (100)^† (94–100)	30 (97)^† (83–100)	50 (98)^† (90–100)	53 (100)^† (93–100)	21 (84)^† (64–95)	57 (98)^† (91–100)	54 (100)^† (93–100)
Pre-booster	n = 21	n = 22	n = 24	n = 31	n = 11	n = 36	n = 41	n = 19	n = 52	n = 46
Day 366 (from day 1)	18 (86) (64–97)	21 (95) (77–100)	24 (100) (86–100)	31 (100) (89–100)	10 (91) (59–100)	33 (92) (78–98)	37 (90) (77–97)	9 (47) (24–71)	43 (83) (70–92)	42 (91) (79–98)
Post-booster	n = 19	n = 20	n = 20	n = 29	n = 10	n = 32	n = 38	n = 17	n = 47	n = 40
Day 387 (from day 1)	19 (100) (82–100)	20 (100) (83–100)	20 (100) (83–100)	29 (100) (88–100)	10 (100) (69–100)	32 (100) (89–100)	38 (100) (91–100)	17 (100) (80–100)	46 (98) (89–100)	40 (100) (91–100)
Day 387 (from day 366)	17 (89)^† (67–99)	16 (80)^† (56–94)	19 (95)^† (75–100)	29 (100)^† (88–100)	10 (100)^† (69–100)	30 (94)^† (79–99)	36 (95)^† (82–99)	17 (100)^† (80–100)	40 (85)^† (72–94)	36 (90)^† (76–97)

*Data presented for days 1–366 are derived from a re-analysis of the original dataset following protocol violation regarding the administration of the booster. This violation required the retrospective removal of the non-compliant site data from the original data set. Data presented for the booster correspond to the original dataset as the non-compliant site did not contribute post-booster data. ^†Percentage of subjects achieving seroconversion or significant increase in hemagglutination inhibition is ≥40 %.

Table 5. Number (percentage and 95% confidence interval) of subjects with hemagglutination inhibition ≥1:330 (per-protocol set)

	Cohort 1 (9–17 years)		Cohort 2 (3–8 years)			Cohort 3 (1–<3 years)			Cohort 4 (6–11 months)
	3.75 μg +halfM F59 (n = 72 )	7.5 μg +fullM F59 (n = 71 )	3.75 μg +halfM F59 (n = 58 )	7.5 μg +fullM F59 (n = 60 )	15 μg +noM F59 (n = 31 )	3.75 μg +halfM F59 (n = 51 )	7.5 μg +fullM F59 (n = 53 )	15 μg +noM F59 (n = 25 )	3.75 μg +halfM F59 (n = 58 )	7.5 μg +fullM F59 (n = 54 )
Day 1	1 (1) (0.035–7)	0 (0) (0–5)	0 (0) (0–6)	0 (0) (0–6)	0 (0) (0–11)	3 (6) (1–16)	4 (8) (2–18)	3 (12) (3–31)	4 (7) (2–17)	4 (7) (2–18)
Day 22	10 (14) (7–24)	13 (18) (10–29)	2 (3) (0–12)	2 (3) (0–12)	2 (6) (1–21)	6 (12) (4–24)	7 (13) (5–25)	5 (20) (7–41)	11 (19) (10–31)	10 (19) (9–31)
Day 43	37 (51) (39–63)	35 (49) (37–61)	37 (64) (50–76)	41 (68) (55–80)	3 (10) (2–26)	38 (75) (60–86)	50 (94) (84–99)	6 (24) (9–45)	41 (71) (57–82)	45 (83) (71–92)
Pre-booster	n = 21	n = 22	n = 24	n = 31	n = 11	n = 36	n = 41	n = 19	n = 52	n = 46
Day 366	4 (19) (5–42)	5 (23) (8–45)	1 (4) (0–21)	4 (13) (4–30)	0 (0) (0–28)	5 (14) (5–29)	10 (24) (12–40)	4 (21)
(6–46)	13 (25) (14–39)	17 (37) (23–52)
Post-booster	n = 19	n = 20	n = 20	n = 29	n = 10	n = 32	n = 38	n = 17	n = 47	n = 40
Day 387	18 (95) (74–100)	19 (95) (75–100)	20 (100) (83–100)	29 (100) (88–100)	9 (90) (55–100)	30 (94) (79–99)	38 (100) (91–100)	16 (94) (71–100)	47 (100) (92–100)	40 (100) (91–100)

Table 6. Summary of immunogenicity data based on the microneutralization (MN) assay (per-protocol set)*

Cohort 1 (9–17 years)		3.75 μg +halfMF59 (n = 72)	7.5 μg +fullMF59 (n = 71)
GMTs and GMRs (95% CI)	Day 1	5.84 (5.06–6.74)	5.21 (4.53–5.99)
	Day 22	84 (61–116)	150 (109–205)
	Day 22 over day 1	14 (11–20)	29 (21–39)
	Day 43	323 (260–402)	557 (452–687)
	Day 43 over day 1	55 (44–70)	107 (85–134)
	Pre-booster	n = 21	n = 22
	Day 366	63 (35–112)	66 (38–112)
	Day 366 over day 1	11 (6.66–20)	12 (7.27–20)
	Post-booster	n = 19	n = 20
	Day 387	1239 (616–2495)	1351 (746–2446)
	Day 387 over day 1	227 (98–526)	245 (120–499)
	Day 387 over day 366	16 (5.75–43)	20 (8.37–46)
Subjects (n,%) with MN titers ≥1:40 (95% CI)		n = 72	n = 71
	Day 1	3 (4) (1–12)	0 (0) (0–5)
	Day 22	55 (76) (65–86)	67 (94) (86–98)
	Day 43	72 (100) (95–100)	71 (100) (95–100)
	Pre-booster	n = 21	n = 22
	Day 366	15 (71) (48–89)	18 (82) (60–95)
	Post-booster	n = 19	n = 20
	Day 387	(95) (74–100)	20 (100) (83–100)
Subjects (n,%) with an at least 4-fold increase in MN titers (95% CI)		n = 72	n = 71
	Day 22	62 (86) (76–93)	68 (96) (88–99)
	Day 43	71 (99) (93–100)	71 (100) (95–100)
	Pre-booster	n = 21	n = 22
	Day 366 to day 1	17 (81) (58–95)	19 (86) (65–97)
	Post-booster	n = 19	n = 20
	Day 387 to day 1	(95) (74–100)	20 (100) (83–100)
	Day 387 to day 366	(89) (67–99)	(85) (62–97)
Cohort 2 (3–8 years)		3.75 μg +halfMF59 (n = 58)	7.5 μg +fullMF59 (n = 60)	15 μg +noMF59 (n = 31)
GMTs and GMRs (95% CI)	Day 1	5.08 (4.59–5.62)	5.16 (4.69–5.68)	5.37 (4.76–6.07)
	Day 22	50 (31–82)	64 (41–100)	33 (19–60)
	Day 22 over day 1	9.93 (6.16–16)	12 (7.89–19)	6.22 (3.51–11)
	Day 43	536 (400–719)	668 (507–879)	160 (113–228)
	Day 43 over day 1	106 (78–144)	129 (97–173)	30 (21–43)
	Pre-booster	n = 24	n = 31	n = 11
	Day 366	56 (33–93)	100 (64–156)	40 (21–76)
	Day 366 over day 1	10 (6.13–18)	19 (12–29)	7.49 (3.89–14)
	Post-booster	n = 20	n = 29	n = 10
	Day 387	4190 (2442–7188)	4411 (2797–6956)	2232 (1149–4338)
	Day 387 over day 1	775 (416–1444)	817 (483–1381)	416 (193–895)
	Day 387 over day 366	75 (43–132)	45 (28–72)	53 (27–106)
Subjects (n,%) with MN titers ≥1:40 (95% CI)		n = 58	n = 60	n = 31
	Day 1	0 (0) (0–6)	1 (2) (0.042–9)	0 (0) (0–11)
	Day 22	35 (60) (47–73)	44 (73) (60–84)	18 (58) (39–75)
	Day 43	57 (98) (91–100)	60 (100) (94–100)	26 (84) (66–95)
	Pre-booster	n = 24	n = 31	n = 11
	Day 366	17 (71) (49–87)	28 (90) (74–98)	6 (55) (23–83)
	Post-booster	n = 20	n = 29	n = 10
	Day 387	20 (100) (83–100)	29 (100) (88–100)	10 (100) (69–100)
Subjects (n,%) with an at least 4-fold increase in MN titers (95% CI)		n = 58	n = 60	n = 31
	Day 22	46 (79) (67–89)	49 (82) (70–90)	17 (55) (36–73)
	Day 43	58 (100) (94–100)	60 (100) (94–100)	30 (97) (83–100)
	Pre-booster	n = 24	n = 31	n = 11
	Day 366 to day 1	22 (92) (73–99)	30 (97) (83–100)	8 (73) (39–94)
	Post-booster	n = 20	n = 29	n = 10
	Day 387 to day 1	20 (100) (83–100)	29 (100) (88–100)	10 (100) (69–100)
	Day 387 to day 366	20 (100) (83–100)	29 (100) (88–100)	10 (100) (69–100)
Cohort 3 (12–35 months)		3.75 μg +halfMF59 (n = 51)	7.5 μg + fullMF59 (n = 54)	15 μg +noMF59 (n = 25)
GMTs and GMRs (95% CI)	Day 1	5.05 (2.88–8.88)	6.14 (3.68–10)	8.71 (4.45–17)
	Day 22	21 (8.17–52)	32 (14–73)	14 (4.74–43)
	Day 22 over day 1	4.07 (2.19–7.56)	5.15 (2.94–9.02)	1.63 (0.78–3.42)
	Day 43	580 (352–957)	764 (486–1203)	100 (55–181)
	Day 43 over day 1	115 (76–174)	125 (85–182)	11 (6.96–19)
	Pre-booster	n = 36	n = 41	n = 19
	Day 366	175 (82–370)	292 (147–579)	71 (30–171)
	Day 366 over day 1	26 (13–53)	42 (22–79)	5.98 (2.64–14)
	Post-booster	n = 31	n = 38	n = 17
	Day 387	5645 (3371–9452)	6505 (4091–10343)	2983 (1628–5464)
	Day 387 over day 1	735 (308–1754)	998 (456–2182)	232 (83–643)
	Day 387 over day 366	28 (12–62)	23 (11–48)	46 (18–119)
Subjects (n,%) with MN titers ≥1:40 (95% CI)		n = 51	n = 54	n = 25
	Day 1	4 (8) (2–19)	6 (11) (4–23)	5 (20) (7–41)
	Day 22	24 (47) (33–62)	30 (56) (41–69)	7 (28) (12–49)
	Day 43	51 (100) (93–100)	54 (100) (93–100)	20 (80) (59–93)
	Pre-booster	n = 36	n = 41	n = 19
	Day 366	34 (94) (81–99)	40 (98) (87–100)	13 (68) (43–87)
	Post-booster	n = 31	n = 38	n = 17
	Day 387	31 (100) (89–100)	38 (100) (91–100)	17 (100) (80–100)
Subjects (n,%) with an at least 4-fold increase in MN titers (95% CI)		n = 51	n = 54	n = 25
	Day 22	30 (59) (44–72)	40 (74) (60–85)	9 (36) (18–57)
	Day 43	51 (100) (93–100)	54 (100) (93–100)	22 (88) (69–97)
	Pre-booster	n = 36	n = 41	n = 19
	Day 366 to day 1	34 (94) (81–99)	41 (100) (91–100)	9 (47) (24–71)
	Post-booster	n = 31	n = 38	n = 17
	Day 387 to day 1	31 (100) (89–100)	38 (100) (91–100)	17 (100) (80–100)
	Day 387 to day 366	(90) (74–98)	(87) (72–96)	(94) (71–100)
Cohort 4 (6–11 months)		3.75 μg +halfMF59 (n = 58)	7.5 μg +fullMF59 (n = 54)
GMTs and GMRs (95% CI)	Day 1	8.78 (3.34–23)	8.59 (3.25–23)
	Day 22	25 (5.77–105)	46 (11–197)
	Day 22 over day 1	2.8 (1.32–5.97)	5.36 (2.51–11)
	Day 43	759 (387–1486)	1039 (529–2038)
	Day 43 over day 1	86 (49–153)	121 (68–214)
	Pre-booster	n = 52	n = 46
	Day 366	195 (105–364)	388 (198–758)
	Day 366 over day 1	24 (12–50)	50 (23–110)
	Post-booster	n = 47	n = 39
	Day 387	9302 (6597–13118)	9482 (6492–13849)
	Day 387 over day 1	1097 (354–3397)	1122 (323–3899)
	Day 387 over day 366	43 (22–84)	23 (11–48)
Subjects (n,%) with MN titers ≥1:40 (95% CI)		n = 58	n = 54
	Day 1	10 (17) (9–29)	9 (17) (8–29)
	Day 22	17 (29) (18–43)	25 (46) (33–60)
	Day 43	58 (100) (94–100)	54 (100) (93–100)
	Pre-booster	n = 52	n = 46
	Day 366	50 (96) (87–100)	46 (100) (92–100)
	Post-booster	n = 47	n = 39
	Day 387	47 (100) (92–100)	39 (100) (91–100)
Subjects (n,%) with an at least 4-fold increase in MN titers (95% CI)		n = 58	n = 54
	Day 22	25 (43) (30–57)	32 (59) (45–72)
	Day 43	58 (100) (94–100)	54 (100) (93–100)
	Pre-booster	n = 52	n = 46
	Day 366 to day 1	47 (90) (79–97)	43 (93) (82–99)
	Post-booster	n = 47	n = 39
	Day 387 to day 1	(98) (89–100)	(97) (87–100)
	Day 387 to day 366	(83) (69–92)	(79) (64–91)

*Data presented for days 1–366 are derived from a re-analysis of the original dataset following protocol violation regarding the administration of the booster. This violation required the retrospective removal of the non-compliant site data from the original dataset. Data presented for the booster correspond to the original dataset as the non-compliant site did not contribute post-booster data. CI, confidence interval; GMR, geometric mean ratio; GMT, geometric mean titer.

Table 7. Numbers (%) of subjects with any (and severe/>100 mm) local reaction within 7 days after each vaccination (safety population)

		First vaccination		Second vaccination		Booster vaccination
Cohort 1 (9–17 years)		3.75 μg +halfM F59 (n = 79 )	7.5 μg +fullM F59 (n = 79 )	3.75 μg +halfM F59 (n = 77 )	7.5 μg +fullM F59 (n = 78 )	3.75 μg +halfM F59 → trivalent seasonal MF59 vaccine (n = 23 )	7.5 μg +fullM F59 → trivalent seasonal MF59 vaccine (n = 24 )
Ecchymosis	Any	3 (4)	5 (6)	3 (4)	2 (3)	2 (9)	0
	>100 mm	0	0	0	0	0	0
Erythema	Any	6 (8)	7 (9)	4 (5)	10 (13)	2 (9)	3 (13)
	>100 mm	0	0	0	0	0	0
Induration	Any	9 (11)	12 (15)	7 (9)	5 (6)	5 (22)	3 (13)
	>100 mm	0	0	0	0	0	0
Swelling	Any	5 (6)	10 (13)	4 (5)	7 (9)	0	4 (17)
	>100 mm	0	0	0	0	0	0
Pain	Any	54 (68)	65 (82)	42 (55)	43 (55)	17 (74)	19 (79)
	Severe	0	1 (1)	0	1 (1)	3 (13)	2 (8)
Cohort 2 (3–8 years)		First vaccination			Second vaccination			Booster vaccination			Second seasonal vaccination
		3.75 μg +halfMF59 (n = 70 )	7.5 μg +fullMF59 (n = 72 )	15 μg +noMF59 (n = 39 )	3.75 μg +halfMF59 (n = 70 )	7.5 μg +fullMF59 (n = 70 )	15 μg +noMF59 (n = 36 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 30 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n = 35 )	15 μg +noMF59 → trivalent seasonal MF59 vaccine (n = 14 )	3.75 μg +halfMF59 → 2× trivalent seasonal MF59 vaccine (n = 22 )	7.5 μg +fullMF59 → 2× trivalent seasonal MF59 vaccine (n = 26 )	15 μg +noMF59 → 2× trivalent seasonal MF59 vaccine (n = 11 )
Ecchymosis	Any	4 (6)	6 (8)	7 (18)	6 (9)	5 (7)	4 (11)	1 (3)	1 (3)	0	0	1 (4)	0
	>100 mm	0	0	0	0	0	0	0	0	0	0	0	0
Erythema	Any	11 (16)	14 (19)	7 (18)	7 (10)	14 (20)	3 (8)	8 (27)	5 (14)	0	4 (18)	6 (23)	0
	>100 mm	0	0	0	0	0	0	0	0	0	0	0	0
Induration	Any	6 (9)	11 (15)	3 (8)	4 (6)	10 (14)	3 (8)	4 (13)	5 (14)	0	4 (18)	7 (27)	0
	>100 mm	0	0	0	0	0	0	0	0	0	0	0	0
Swelling	Any	5 (7)	7 (10)	2 (5)	5 (7)	5 (7)	2 (6)	3 (10)	5 (14)	1 (7)	4 (18)	5 (19)	1 (9)
	>100 mm	0	0	0	0	0	0	0	0	0	0	0	0
Pain	Any	30 (43)	33 (46)	14 (36)	26/69 (38)	30 (43)	10 (28)	23 (77)	24 (69)	9 (64)	13 (59)	13 (50)	7 (64)
	Severe	1 (1)	2 (3)	0	1/69 (1)	0	0	1 (3)	1 (3)	0	0	1 (4)	0
Cohort 3 (1–<3 years)		First vaccination			Second vaccination			First booster vaccination			Second seasonal vaccination
		3.75 μg +halfMF59 (n = 65 )	7.5 μg +fullMF59 (n = 73 )	15 μg +noMF59 (n = 33 )	3.75 μg +halfMF59 (n = 64 )	7.5 μg +fullMF59 (n = 71 )	15 μg +noMF59 (n = 29 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 42 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n = 51 )	15 μg +noMF59 → trivalent seasonal MF59 vaccine n = 21 )	3.75 μg +halfMF59 → 2× trivalent seasonal MF59 vaccine (n = 36 )	7.5 μg +fullMF59 → 2× trivalent seasonal MF59 vaccine (n = 45 )	15 μg +noMF59 → 2× trivalent seasonal MF59 vaccine n = 17 )
Ecchymosis (mm)	Any	3 (5)	8 (11)	5 (15)	1 (2)	5 (7)	2 (7)	2 (5)	5 (10)	0	0	1 (2)	1 (6)
	>100 mm	0	0	0	0	0	0	0	0	0	0	0	0
Erythema (mm)	Any	8 (12)	12 (16)	6 (18)	6 (9)	11 (15)	4 (14)	6 (14)	13 (25)	4 (19)	10 (28)	10 (22)	2 (12)
	>100 mm	0	0	0	0	1 (1)	0	0	0	0	0	0	0
Induration (mm)	Any	6 (9)	10 (14)	3 (9)	2 (3)	4 (6)	2 (7)	4 (10)	7 (14)	3 (14)	8 (22)	8 (18)	3 (18)
	>100 mm	0	0	0	0	0	0	0	0	0	0	0	0
Swelling (mm)	Any	1 (2)	4 (5)	2 (6)	1 (2)	4 (6)	1 (3)	6 (14)	4 (8)	1 (5)	7 (19)	7 (16)	2 (12)
	>100 mm	0	1 (1)	0	0	0	0	0	0	0	0	0	0
Tenderness	Any	7 (11)	30 (41)	10 (30)	5 (8)	21 (30)	9 (31)	8 (19)	18 (35)	7 (33)	8 (22)	11 (24)	4 (24)
	Cried when injected limb was moved	0	3 (4)	1 (3)	0	1 (1)	0	1 (2)	0	0	0	0	1 (6)
Cohort 4 (6–11 months)		First vaccination		Second vaccination		Booster vaccination		Booster vaccination
		3.75 μg +halfMF59 (n = 75 )	7.5 μg +fullMF59 (n = 74 )	3.75 μg +halfMF59 (n = 71 )	7.5 μg +fullMF59 (n = 70 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 67 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n = 61 )	3.75 μg +halfMF59 → 2× trivalent seasonal MF59 vaccine (n = 63 )	7.5 μg +fullMF59 → 2× trivalent seasonal MF59 vaccine (n = 60 )
Ecchymosis (mm)	Any	2 (3)	0	3 (4)	0	1 (1)	1 (2)	1 (2)	1 (2)
	>100 mm	0	0	0	0	0	0	0	0
Erythema (mm)	Any	6 (8)	5 (7)	9 (13)	3 (4)	5 (7)	9 (15)	6 (10)	6 (10)
	>100 mm	0	0	0	0	0	1 (2)	0	0
Induration (mm)	Any	4 (5)	3 (4)	3 (4)	7 (10)	5 (7)	4 (7)	6 (10)	5 (8)
	>100 mm	0	0	0	0	0	0	0	0
Swelling (mm)	Any	0	0	1 (1)	0	1 (1)	5 (8)	3 (5)	3 (5)
	>100 mm	0	0	0	0	0	0	0	0
Tenderness	Any	9 (12)	17 (23)	12 (17)	18 (26)	11 (16)	19 (31)	14 (22)	13 (22)
	Cried when injected limb was moved	0	2 (3)	0	1 (1)	2 (3)	2 (3)	2 (3)	3 (5)

Table 8. Numbers (%) of subjects with any (and severe) systemic reaction within 7 d after each vaccination (safety population)

		First vaccination		Second vaccination		Booster vaccination
Cohort 1 (9–17 years)		3.75 μg +halfMF59 (n = 79 )	7.5 μg +fullMF59 (n = 79 )	3.75 μg +halfMF59 (n = 77 )	3.75 μg +halfMF59 (n = 78 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 23 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n=24 )
Chills	Any	1 (1)	3 (4)	2 (3)	7 (9)	1 (4)	1 (4)
	Severe	0	0	0	0	0	0
Malaise	Any	6 (8)	9 (11)	6 (8)	8 (10)	5 (22)	3 (13)
	Severe	1 (1)	0	0	0	0	0
Myalgia	Any	16 (20)	16 (20)	8 (10)	8 (10)	7 (30)	8 (33)
	Severe	1 (1)	0	0	0	0	0
Arthralgia	Any	6 (8)	8 (10)	6 (8)	4 (5)	1 (4)	2 (8)
	Severe	0	0	0	0	0	0
Headache	Any	18 (23)	23 (29)	11 (14)	10 (13)	5 (22)	5 (21)
	Severe	2 (3)	2 (3)	2 (3)	0	1 (4)	0
Sweating	Any	4 (5)	3 (4)	1 (1)	0	2 (9)	2 (8)
	Severe	0	0	0	0	0	0
Fatigue	Any	16 (20)	21 (27)	12 (16)	11 (14)	4 (17)	2 (8)
	Severe	1 (1)	1 (1)	3 (4)	1 (1)	1 (4)	0
Nausea	Any	5 (6)	6 (8)	4 (5)	3 (4)	4 (17)	2 (8)
	Severe	1 (1)	0	0	0	0	1 (4)
Fever (≥38°C)	Yes	1 (1)	0	2 (3)	1 (1)	1 (4)	0
Other
Temperature (°C)	<38.0°C	78 (99)	79 (100)	75 (97)	77 (99)	22 (96)	24 (100)
	≥40.0°C	0	0	0	0	0	0
Stayed home	Yes	2 (3)	0	3 (4)	3 (4)	3 (13)	2 (8)
Analgesic/antipyretic medications used	Yes	7 (9)	7 (9)	5 (6)	5 (6)	4 (17)	3 (13)
Cohort 2 (3–8 years)		First vaccination			Second vaccination			Booster vaccination			Second seasonal vaccination
		3.75 μg +halfMF59 (n = 70 )	7.5 μg +fullMF59 (n = 72 )	15 μg +noMF59 (n = 39 )	3.75 μg +halfMF59 (n = 69 )	7.5 μg +fullMF59 (n = 70 )	15 μg +noMF59 (n = 36 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 30 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n = 35 )	15 μg +noMF59 → trivalent seasonal MF59 vaccine (n = 14 )	3.75 μg +halfMF59 → 2× trivalent seasonal MF59 vaccine (n = 22 )	7.5 μg +fullMF59 → 2× trivalent seasonal MF59 vaccine (n = 26 )	15 μg +noMF59 → 2× trivalent seasonal MF59 vaccine (n = 11 )
Chills	Any	3 (4)	2 (3)	0	1 (1)	5 (7)	2 (6)	3 (10)	5 (14)	0	0	1 (4)	0
	Severe	0	0	0	0	0	0	0	2 (6)	0	0	0	0
Malaise	Any	9 (13)	3 (4)	6 (15)	4 (6)	4 (6)	4 (11)	8 (27)	11 (31)	0	1 (5)	2 (8)	1 (9)
	Severe	2 (3)	2 (3)	0	0	0	0	0	1 (3)	0	1 (5)	0	0
Myalgia	Any	5 (7)	3 (4)	2 (5)	2 (3)	8 (11)	2 (6)	4 (13)	9 (26)	4 (29)	1 (5)	2 (8)	1 (9)
	Severe	0	0	0	0	0	0	0	1 (3)	0	0	0	0
Arthralgia	Any	2 (3)	3 (4)	0	3 (4)	3 (4)	2 (6)	5 (17)	5 (14)	2 (14)	1 (5)	2 (8)	1 (9)
	Severe	0	0	0	0	0	0	0	0	0	0	0	0
Headache	Any	7 (10)	5 (7)	1 (3)	1 (1)	4 (6)	6 (17)	10 (33)	11 (31)	1 (7)	3 (14)	3 (12)	1 (9)
	Severe	2 (3)	1 (1)	0	0	0	0	0	1 (3)	0	0	0	0
Sweating	Any	1 (1)	1 (1)	0	0	0	0	2 (7)	3 (9)	0	0	1 (4)	0
	Severe	0	0	0	0	0	0	0	1 (3)	0	0	0	0
Fatigue	Any	17 (24)	15 (21)	7 (18)	8 (12)	10 (14)	5 (14)	7 (23)	10 (29)	1 (7)	3 (14)	6 (23)	2 (18)
	Severe	2 (3)	3 (4)	0	0	0	0	0	1 (3)	0	0	0	0
Nausea	Any	2 (3)	5 (7)	2 (5)	3 (4)	1 (1)	2 (6)	4 (13)	6 (17)	1 (7)	1 (5)	2 (8)	1 (9)
	Severe	1 (1)	1 (1)	0	0	0	0	0	1 (3)	0	1 (5)	0	0
Fever (≥38 °C)	Yes	7 (10)	4 (6)	0	3 (4)	3 (4)	3 (8)	0	8 (23)	0	1 (5)	2 (8)	1 (9)
Other
Temperature	<38.0°C	63 (90)	68 (94)	39 (100)	66 (96)	67 (96)	33 (92)	30 (100)	27 (77)	14 (100)	21 (95)	24 (92)	10 (91)
	≥40.0°C	0	0	0	0	0	0	0	0	0	0	0	0
Stayed home	Yes	5 (7)	10 (14)	0	1 (1)	6 (9)	3 (8)	3 (10)	10 (29)	0	1 (5)	0	0
Analgesic/ antipyretic medications used	Yes	9 (13)	11 (15)	4 (10)	2 (3)	7 (10)	2 (6)	4 (13)	8 (23)	1 (7)	2 (9)	6 (23)	1 (9)
Cohort 3 (1–<3 years)		First vaccination			Second vaccination			Booster vaccination			Second seasonal vaccination
		3.75 μg +halfMF59 (n = 65 )	7.5 μg +fullMF59 (n = 73 )	15 μg +noMF59 (n = 33 )	3.75 μg +halfMF59 (n = 64 )	7.5 μg +fullMF59 (n = 71 )	15 μg +noMF59 (n = 29 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 42 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n = 51 )	15 μg +noMF59 → trivalent seasonal MF59 vaccine (n = 21 )	3.75 μg +halfMF59 → 2× trivalent seasonal MF59 vaccine (n = 36 )	7.5 μg +fullMF59 → 2× trivalent seasonal MF59 vaccine (n = 45 )	15 μg +noMF59 → 2× trivalent seasonal MF59 vaccine (n=17 )
Sleepiness	Present	14 (22)	23 (32)	7 (21)	11 (17)	13 (18)	4 (14)	9 (21)	6 (12)	1 (5)	1 (3)	1 (2)	1 (6)
Diarrhea	Present	15 (23)	17 (23)	6 (18)	10 (16)	10 (14)	4 (14)	6 (14)	4 (8)	1 (5)	3 (8)	3 (7)	0
Vomiting	Present	7 (11)	11 (15)	2 (6)	5 (8)	8 (11)	1 (3)	1 (2)	2 (4)	0	1 (3)	1 (2)	0
Irritability	Present	17 (26)	17 (23)	5 (15)	9 (14)	6 (8)	2 (7)	5 (12)	3 (6)	3 (14)	2 (6)	3 (7)	3 (18)
Change in eating habits	Present	14 (22)	18 (25)	4 (12)	12 (19)	11 (15)	4 (14)	5 (12)	4 (8)	1 (5)	3 (8)	2 (4)	1 (6)
Shivering	Present	3 (5)	2 (3)	1 (3)	4 (6)	4 (6)	1 (3)	1 (2)	3 (6)	0	1 (3)	0	0
Unusual crying	Present	15 (23)	22 (30)	7 (21)	11 (17)	11 (15)	3 (10)	3 (7)	4 (8)	1 (5)	1 (3)	3 (7)	1 (6)
Fever ( ≥38 °C)	Yes	8 (12)	8 (11)	4 (12)	12 (19)	7 (10)	1 (3)	6 (14)	15 (29)	2 (10)	3 (8)	4 (9)	0
Other
Temperature	<38.0°C	57 (88)	65 (89)	29 (88)	52 (81)	64 (90)	28 (97)	36 (86)	36 (71)	19 (90)	33 (92)	41 (91)	17 (100)
	≥40.0°C	0	0	0	0	1 (1)	0	1 (2)	0	1 (5)	0	0	0
Stayed home	Yes	6 (9)	8 (11)	2/32 (6)	8 (13)	2 (3)	3 (10)	5/41 (12)	1/50 (2)	2 (10)	1 (3)	0	0
Analgesic antipyretic medications used	Yes	15 (23)	21 (29)	8/32 (25)	18 (28)	15 (21)	8 (28)	8 (19)	15 (29)	5 (24)	3 (8)	6 (13)	1 (6)
Cohort 4 (6–11 months)		First vaccination		Second vaccination		Booster vaccination		Second seasonal vaccination
		3.75 μg +halfMF59 (n = 75 )	7.5 μg +fullMF59 (n = 74 )	3.75 μg +halfMF59 (n = 71 )	7.5 μg +fullMF59 (n = 70 )	3.75 μg +halfMF59 → trivalent seasonal MF59 vaccine (n = 67 )	7.5 μg +fullMF59 → trivalent seasonal MF59 vaccine (n = 61 )	3.75 μg +halfMF59 → 2× trivalent seasonal MF59 vaccine (n = 63 )	7.5 μg +fullMF59 → 2× trivalent seasonal MF59 vaccine (n = 60 )
Sleepiness	Present	12 (16)	15 (20)	10 (14)	13 (19)	5 (7)	10 (16)	3 (5)	5 (8)
Diarrhea	Present	20 (27)	22 (30)	13 (18)	20 (29)	8 (12)	6 (10)	7 (11)	7 (12)
Vomiting	Present	12 (16)	11 (15)	8 (11)	10 (14)	2 (3)	1 (2)	5 (8)	2 (3)
Irritability	Present	9 (12)	11 (15)	9 (13)	6 (9)	3 (4)	6 (10)	4 (6)	2 (3)
Change in eating habits	Present	13 (17)	21 (28)	10 (14)	12 (17)	2 (3)	7 (11)	6 (10)	5 (8)
Shivering	Present	3 (4)	2 (3)	2 (3)	4 (6)	3 (4)	2 (3)	2 (3)	1 (2)
Unusual crying	Present	20 (27)	16 (22)	15 (21)	17 (24)	4 (6)	9 (15)	8 (13)	3 (5)
Fever ( ≥38 °C )	Yes	7 (9)	7 (9)	7 (10)	12 (17)	9 (13)	13 (21)	7 (11)	10 (17)
Other
Temperature	<38.0°C	68 (91)	67 (91)	64 (90)	58 (83)	58 (87)	48 (79)	56 (89)	50 (83)
	≥40.0°C	0	1 (1)	1 (1)	0	1 (1)	0	0	0
Stayed home	Yes	8 (11)	5 (7)	7 (10)	7 (10)	5 (7)	5 (8)	2 (3)	3 (5)
Analgesic/antipyretic medications used	Yes	16 (21)	21 (28)	16 (23)	17 (24)	13 (19)	19 (31)	10 (16)	11 (18)