Table 2 Multiplicative and additive interactions between sex and birth order with non-NIP vaccination

First-born

reference

reference

reference

reference

Second-born

 Crude model

0.82 (0.70, 0.94)

0.008

0 (−0.19, 0.18)

0 (−0.25, 0.24)

1.01 (0.51, 2.03)

 Multivariable model 1

0.82 (0.70, 0.94)

0.007

−0.01 (−0.19, 0.18)

−0.01 (−0.26, 0.24)

1.03 (0.51, 2.05)

 Multivariable model 2

0.86 (0.75, 0.98)

0.034

0.01 (−0.16, 0.19)

0.02 (−0.2, 0.23)

0.94 (0.4, 2.22)

Third-born or later

 Crude model

0.53 (0.37, 0.72)

 <.001

−0.07 (−0.32, 0.18)

−0.15 (−0.69, 0.4)

1.15 (0.68, 1.95)

 Multivariable model 1

0.54 (0.37, 0.72)

 <.001

−0.07 (−0.32, 0.18)

−0.14 (−0.69, 0.4)

1.15 (0.68, 1.96)

 Multivariable model 2

0.76 (0.53, 1.04)

0.115

−0.11 (−0.44, 0.22)

−0.16 (−0.65, 0.34)

1.61 (0.35, 7.42)