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Table 3 Effect of race for 2014–2015 IAV-H3N2 and sex for 2015–2016 IBV on unadjusted and adjusted ratios of pre-vaccination HAI titers over prior season post-vaccination HAI titersa

From: Interseason waning of vaccine-induced hemagglutination inhibition antibody titers and contributing factors to pre-existing humoral immunity against influenza in community-dwelling older adults 75 years and older

Vaccine strain

Consecutive two seasons

Unadjusted

Adjustedb

IAV-H3N2

2014–2015 white (n = 42)

0.70 (0.53–0.93) (p < .012)

1.00 (0.65–1.53) (p = .9980)

2014–2015 non-white (n = 7)

0.62 (0.30–1.29) (p = .200)

0.39 (0.19–0.84) (p = .0154)

IBV

2015–2016 male (n = 20)

0.73 (0.59–0.90) (p = .0038)

0.65 (0.47–0.90) (p = .0089)

2015–2016 female (n = 32)

0.76 (0.61–0.94) (p = .0122)

0.83 (0.52–1.32) (p = .4278)

  1. aPre-vaccination and prior season post-vaccination HAI antibody titers were both measured using the respective prior season vaccine strain antigens
  2. bAdjusted for age at prior study season, sex, race, and education