Table 2. Effectiveness of Influenza Vaccine for Children in 2013/14 Influenza Season (N = 4727).
| Any Influenza e | Type A e | A(H1N1)pdm09 f | Type B e | ||||||
|---|---|---|---|---|---|---|---|---|---|
| VE% (95% CI) | VE% (95% CI) | VE% (95% CI) | VE% (95% CI) | ||||||
| All Ages 6 mo-15 y/o | Crude | 45 (38–51) | (880/2281) [1303/2446]* | 62 (55–68) | (265/876) [1303/2446]* | 77 (59–87) | (17/66) [281/468]* | 32 (22–40) | (615/1405) [1303/2446]* |
| Adjusted a , b | 45 (39–52) | 63 (56–69) | 77 (59–87) | 26 (14–36) | |||||
| Adjusted a , b , c | 45 (38–52) | 63 (56–69) | 77 (59–88) | 25 (13–35) | |||||
| Adjusted a , b , d | 51 (43–58) | 67(59–74) | 85 (65–93) | 33 (20–45) | |||||
| Age 6–11 m/o | Crude | 24 (-77-68) | (8/49) [34/166] | 29 (-82-73) | (6/39) [34/166] | NA g | (0/2) [8/36] | NA g | (2/10) [34/166] |
| Adjusted a | 21 (-87-67) | 30 (-85-74) | NA g | NA g | |||||
| Age 1–2 y/o | Crude | 61 (49–70) | (114/342) [451/803] | 70 (58–78) | (63/224) [451/803] | 67 (15–87) | (8/21) [102/157] | 41(12–60) | (51/118) [451/803] |
| Adjusted a | 63 (51–72) | 72 (60–80) | 67 (15–87) | 41 (10–61) | |||||
| Age 6 m/o-2 y/o | Crude | 55 (42–65) | (122/391) [485/969] | 65 (52–74) | (69/263) [485/969] | 60 (1–84) | (8/23) [110/193] | 30 (-2-52) | (53/128) [485/969] |
| Adjusted a | 57 (44–67) | 67 (54–76) | 62 (4–85) | 29 (-6-52) | |||||
| Age 3–5 y/o | Crude | 58 (48–67) | (208/539) [406/675] | 72 (62–80) | (73/248) [406/675] | 85 (44–96) | (3/17) [78/134] | 43 (24–57) | (135/291) [406/675] |
| Adjusted a | 60 (49–69) | 73 (63–81) | 84 (43–96) | 44 (25–58) | |||||
| Age 6–12 y/o | Crude | 36 (23–47) | (495/1169) [371/694] | 55 (41–66) | (113/331) [371/694] | 88 (64–96) | (5/23) [85/123] | 27 (11–40) | (382/838) [371/694] |
| Adjusted a | 39 (26–50) | 58 (44–69) | 90 (67–97) | 30 (13–43) | |||||
| Age 13–15 y/o | Crude | 29 (-17-57) | (55/182) [41/108] | 32 (-57-70) | (10/34) [41/108] | NA g | (1/3) [8/18] | 29 (-21-58) | (45/148) [41/108] |
| Adjusted a | 22 (-33-54) | 12 (-115-64) | NA g | 23 (-34-56) | |||||
a Adjusted for comorbidity (yes or no, except H1N1 analysis), area (north area, middle area, south of the Kanto region), months of onset.
b Adjusted for age (0–15 y/o).
c Adjusted for time tested after the onset (<12, 12–48 and >48 hours).
d Patients tested only >12 hours after onset.
Data for 3046 patients were available; 1499 for any influenza (A; 537, H1N1; 43, B; 962) and 1547 for influenza negative.
e Two hospitals have no information on comorbidity.
f Only four institutes used IRDTs that can detect A(H1N1)pdm09. One hospital had no information on comorbidity.
g Not analyzed because few patients developed influenza.
* (vaccinated/cases) [vaccinated/controls].