Sara van den Berg

33 2 CMV on influenza vaccination titers and protection rate after the seasonal vaccination were higher for both H1N1pdm and H3N2 in the high anti-CMV IgG levels group compared to low anti-CMV IgG levels group within the CMV-seropositive individuals at most time points after vaccination ( Figure 4, E, F, G; Supplemental table 5, 7 ). In summary, although no clear effect of age or CMV-serostatus, high-anti CMV IgG levels seem to be associated with high influenza antibody titers and protection rate in CMV-seropositive individuals. Figure 3. Effect of latent CMV infection on influenza virus-specific antibody titer and protection rate to pandemic influenza infection. Geometric mean and 95% CI of influenza antibody titers and the percentage protected (defined as a titer ≥ 40) are shown for CMV-seropositive and CMV- seronegative individuals ( A, B ) and for CMV-seropositive individuals with low, medium and high anti-CMV IgG levels ( C, D ) before and after pandemic vaccination with H1N1pdm in 2009. Arrows (↓) indicate the moment of vaccination. Dotted horizontal line represents a protective influenza titer of 40. Results are adjusted for sex, age group and previous influenza vaccinations by a Generalized Estimation Equation regression model. Significant differences are tested by pairwise comparison between CMV-seropositive and CMV-seronegative individuals or anti-CMV IgG group high and low per separate time point. * p < 0.05 DISCUSSION In this study, we investigated the effect of age and latent CMV infection on the antibody response to a novel influenza vaccine strain in healthy adults. We found evidence of immunosenescence in these adults from the age of 40. However, latent CMV infection did not impair the antibody responses to a de novo influenza vaccine response. Interestingly, indications for the contrary were observed: CMV-seropositive individuals even showed a higher long-term influenza protection rate after pandemic influenza vaccination. These results suggest that latent CMV infection does not always further weaken age-related impaired immunity, but if anything, might be beneficial.