Influenza vaccination effectiveness for people aged under 65 years in Japan, 2013/2014 season: application of a doubly robust method to a large-scale, real-world dataset

Table 3 Incidence of influenza onset and odds ratios (OR_DR) for influenza vaccination

Age	1–64 years	1–4 years	5–12 years	13–19 years	20–64 years
Age	No. (%)	No. (%)	No. (%)	No. (%)	No. (%)
Outcome definition	OR_DR (95% CI)	OR_DR (95% CI)	OR_DR (95% CI)	OR_DR (95% CI)	OR_DR (95% CI)
Influenza diagnosis codes only ^a	50,487 (13.7)	9093 (19.1)	24,315 (25.9)	6366 (12.7)	10,674 (6.0)
Influenza diagnosis codes only ^a	0.775 (0.757–0.794)	0.600 (0.567–0.633)	0.770 (0.741–0.800)	0.938 (0.879–0.997)	0.747 (0.708–0.786)
Influenza diagnosis codes + Prescription of antiviral drugs	46,425 (12.6)	7489 (15.7)	22,941 (24.5)	5975 (11.9)	9965 (5.6)
Influenza diagnosis codes + Prescription of antiviral drugs	0.772 (0.753–0.791)	0.562 (0.528–0.595)	0.775 (0.745–0.805)	0.941 (0.881–1.002)	0.744 (0.704–0.783)
Influenza diagnosis codes + Use of rapid testing	46,389 (12.6)	6528 (13.7)	23,539 (25.1)	6141 (12.3)	10,122 (5.7)
Influenza diagnosis codes + Use of rapid testing	0.784 (0.765–0.803)	0.572 (0.536–0.609)	0.773 (0.743–0.803)	0.930 (0.871–0.989)	0.750 (0.710–0.790)
ICD10 J101 code + Use of rapid testing ^b	28,407 (7.7)	4052 (8.5)	14,594 (15.5)	3664 (7.3)	6061 (3.4)
ICD10 J101 code + Use of rapid testing ^b	0.793 (0.769–0.817)	0.581 (0.536–0.626)	0.796 (0.760–0.833)	0.908 (0.835–0.981)	0.771 (0.719–0.824)

For each outcome, we excluded subjects who had the outcome within 13 days after vaccination. Therefore, the number of study subjects in an age strata differed by outcome definition. All confounders were adjusted using a doubly robust method
^a Defined by ICD-10 influenza diagnosis codes (J101, J110, J111, J118)
^b Defined by combination of ICD-10 influenza diagnosis codes (J101: influenza due to identified seasonal influenza virus) with use of a rapid-testing as outcome

ISSN: 1471-2334