Table 4 Multivariate logistic regression analyses for SCR and post-vaccination SPR in participants with pre-vaccination HAI antibody titer < 40

H1N1 (N = 124)

 Age, years

0.955(0.92–0.992)

0.018

0.963(0.922–1.006)

0.091

 IV history

0.341(0.122–0.952)

0.04

0.362(0.118–1.114)

0.076

 Post-vaccination HAI

1.028(0.955–1.106)

0.461

1.165(1.062–1.277)

0.001

H3N2 (N = 139)

 Age, years

1.006(0.975–1.037)

0.722

1.023(0.987–1.06)

0.218

 IV history

0.537(0.235–1.228)

0.141

0.461(0.175–1.21)

0.116

 Post-vaccination HAI

0.933(0.878–0.992)

0.027

1.099(1.016–1.189)

0.018

B/Victoria (N = 133)

 Age, years

0.949(0.911–0.988)

0.011

0.947(0.901–0.996)

0.035

 IV history

0.461(0.164–1.291)

0.14

0.348(0.099–1.224)

0.1

 Post-vaccination HAI

1.044(0.967–1.127)

0.275

1.148(1.038–1.27)

0.007

B/Yamagata (N = 62)

 Age, years

0.764(0.629–0.929)

0.007

0.752(0.573–0.988)

0.041

 IV history

0.655(0.034–12.529)

0.779

0.015(0.000–11.705)

0.217

 Post-vaccination HAI

0.915(0.76–1.103)

0.352

1.255(0.931–1.691)

0.136