Table 3.

Vaccine Effectiveness by the Number of Vaccine Doses in Children.

a) Multivariate logistic regression analysis
1) Total
	Adjusted odds ratiosa(95% CI)
	Zero doses	One dose	Two doses	p value
Any Influenza	1.0	0.76 (0.63-0.91)	0.57 (0.40-0.83)	0.0033 *
Influenza total A	1.0	0.78 (0.64-0.94)	0.60 (0.42-0.88)	0.0081 *
Influenza A (H1N1) pdm09	1.0	0.76 (0.58-0.98)	0.57 (0.34-0.97)	0.0378 *
Influenza A (H3N2)	1.0	0.78 (0.63-0.96)	0.60 (0.39-0.92)	0.0201*
2) ≤ 6 yearsb
Any Influenza	1.0	0.76 (0.60-0.96)	0.58 (0.36-0.93)	0.0240 *
Influenza total A	1.0	0.76 (0.60-0.97)	0.58 (0.36-0.94)	0.0272 *
Influenza A (H1N1) pdm09	1.0	0.69 (0.49-0.98)	0.48 (0.24-0.96)	0.0383 *
Influenza A (H3N2)	1.0	0.79 (0.61-1.03)	0.62 (0.37-1.07)	0.0850
3) 7-12 years
Any Influenza	1.0	0.76 (0.56-1.03)	0.57 (0.31-1.05)	0.0725
Influenza total A	1.0	0.80 (0.59-1.09)	0.64 (0.35-1.19)	0.1560
Influenza A (H1N1) pdm09	1.0	0.90 (0.59-1.36)	0.80 (0.35-1.84)	0.6067
Influenza A (H3N2)	1.0	0.75 (0.52-1.07)	0.56 (0.27-1.15)	0.1114
b) Pearson’s Chi-square test and Fischer’s exact test
1) Total
	Influenza infection (Yes: No)
	One dose	Two doses	p value
Any Influenza	38:46	87:119	0.6393
Influenza total A	36:46	87:119	0.7960
Influenza A (H1N1) pdm09	9:46	34:119	0.4394†
Influenza A (H3N2)	27:46	53:119	0.3461
2) ≤ 6 yearsb
Any Influenza	16:22	59:81	0.9967
Influenza total A	16:22	59:81	0.9967
Influenza A (H1N1) pdm09	2:22	20:81	0.2423†
Influenza A (H3N2)	14:22	39:81	0.4778
3) 7-12 years
Any Influenza	22:24	28:38	0.5716
Influenza total A	20:24	28:38	0.7536
Influenza A (H1N1) pdm09	7:24	14:38	0.7959†
Influenza A (H3N2)	13:24	14:38	0.4062

CI: confidence interval

Influenza total A: Influenza A (H1N1) pdm09 and Influenza A (H3N2)

* Statistically significant

† Fischer’s exact test

^aAdjusted for age (years), body temperature (°C), time from onset (hours)

^bEighteen patients aged ≤ 11 months were included.