Figure 3.

Adjusted rOR of IIV3 versus IIV4 (reference) during 4 seasons from 2013–2014 to 2016–2017 of any influenza B; of each B lineage virus infection, including B/Yamagata– or B/Victoria–containing IIV3 seasons; and of the B lineage virus included in IIV3 versus lineage-mismatched IIV3. A priori, rOR estimates were simple adjusted for age, season, site, calendar week (pre-peak and peak influenza activity and post-peak tertiles, per site per season) and the presence of any high-risk, chronic medical condition. Data were not reported when the number of vaccinated cases was <5. Abbreviations: CI, confidence interval; IIV3, trivalent inactivated influenza vaccine; IIV4, quadrivalent inactivated influenza vaccine; rOR, relative odds ratios.