Season 2014–2015Period at riskIncidence (per 1000 person-years)
(95% CI)
Relative risk
(95% CI)
LAIV recipients
(n=6745)
Matched unvaccinated children
(n=20 163)
Matched
IIV recipients
(n=6738)
LAIV versus no vaccineLAIV versus
IIV
Any hospitalisation42 days231
(198 to 267)
n*=182
251
(230 to 273)
n*=518
503
(455 to 555)
n*=395
0.90
(0.76 to 1.07)
0.42
(0.35 to 0.51)
Hospitalisation for lower respiratory event98
(77 to 122)
n*=77
112
(98 to 128)
n*=232
199
(169 to 232)
n*=156
0.85
(0.65 to 1.10)
0.46
(0.35 to 0.61)
Any hospitalisation6 months178
(164 to 193)
n*=575
164
(155 to 173)
n*=1242
311
(292 to 331)
n*=999
1.08
(0.97 to 1.20)
0.53
(0.47 to 0.59)
Hospitalisation for lower respiratory event75
(66 to 85)
n*=241
74
(68 to 80)
n*=558
120
(108 to 133)
n*=385
1.01
(0.87 to 1.18)
0.59
(0.50 to 0.70)
  • *Number of incident cases.

  • IIV, inactivated influenza vaccine; LAIV, live attenuated influenza vaccine.