Table 5 Multivariate logistic regression analyses for SCR in participants with pre-vaccination HAI antibody titer ≥ 40

H1N1 (N = 43)

 Age, years

1.018(0.945–1.096)

0.634

 IV history

0.006(0.000–0.151)

0.002

 Pre-vaccination HAI

0.997(0.987–1.008)

0.662

H3N2 (N = 28)

 Age, years

——

0.889

 IV history

——

0.89

 Pre-vaccination HAI

——

0.973

B/Victoria (N = 34)

 Age, years

0.993(0.921–1.071)

0.862

 IV history

2.486(0.323–19.153)

0.382

 Pre-vaccination HAI

0.976(0.94–1.014)

0.212

B/Yamagata (N = 105)

 Age, years

1.006(0.971–1.041)

0.752

 IV history

0.339(0.129–0.887)

0.028

 Pre-vaccination HAI

0.99(0.978–1.003)

0.126