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. 2015 Apr 15;2(2):ofv052. doi: 10.1093/ofid/ofv052

Figure 1.

Figure 1.

Assessment of antibody responses to 2008–2009 trivalent inactivated influenza vaccine. A, Serum hemagglutination inhibition (HI) antibody (n = 88) and B, microneutralization titers (n = 90) to H3N2 and H1N1 were assessed on day 0 prior to vaccination and day 28 after vaccination. The geometric mean titer (GMT) ratio (day 28 GMT/day 0 GMT) was calculated to determine the vaccine-associated change in antibody within each age group. A GMT ratio of 1 (dotted line) is indicative of no change. Day 28 GMT ratios were used to compare responses of older adult groups to middle-aged controls (day 28 GMT of older adult group/day 28 GMT of 50–59 age group). A GMT ratio less than 1 (dotted line) is indicative of a lower postvaccination response. Error bars represent 1 standard error. Significance is indicated by *P ≤ .05, **P ≤ .01, †P ≤ .001.