An open-label randomized controlled parallel-group pilot study comparing the immunogenicity of a standard-, double- and booster-dose regimens of the 2014 seasonal trivalent inactivated influenza vaccine in kidney transplant recipients

Background: Immunogenicity of influenza vaccine in transplant recipients is suboptimal and alternative vaccination regimens are necessary. Methods: We compared the immunogenicity of a standard-dose trivalent inactivated influenza vaccination (SDTIIV), double-dose trivalent inactivated influenza vaccination (DDTIIV) and booster-dose trivalent inactivated influenza vaccination (BDTIIV) of the 2014 seasonal trivalent inactivated influenza vaccine in kidney transplant recipients. We randomized 176 participants to SDTIIV (59), DDTIIV (59) and BDTIIV regimens (58). Antibody titres were determined by hemagglutination inhibition at enrollment and 21 days post-vaccination. Seroprotection rates (SPR), seroconversion rates (SCR) and geometric mean ratios (GMR) were analyzed separately for participants with low (<1:40) and high (≥1:40) pre-vaccination antibody titres. Results: Vaccination was confirmed for 172 participants. Immunogenicity analysis was done for 149 participants who provided post-vaccination blood samples. In the subgroup with high pre-vaccination antibody titres, all vaccination regimens induced SPR >70% to all antigens, but SCR and GMR were below the recommendations. In the subgroup with low pre-vaccination antibody titres, DDTIIV and BDTIIV regimens induced adequate SCR >40% and GMR >2,5 for all antigens, while SDTIIV achieved the same outcomes only for influenza B. SPR were >70% only after DDTIIV (A/H1N1 - 77.8%) and BDTIIV (A/H3N2 - 77.8%). BDTIIV regimen independently increased seroprotection to A/H1N1 (PR=2.58; p=0.021) and A/H3N2 (PR=2.21; p=0.004), while DDTIIV independently increased seroprotection to A/H1N1 (PR=2.59; p=0.021). Conclusion: Our results suggest that DDTIIV and BDTIIV regimens are more immunogenic than SDTIIV, indicating the need for head-to-head multicenter clinical trials to further evaluate their efficacy.

Campaign, counseling and compliance with influenza vaccine among older persons

OBJECTIVES: Population aging raises concerns regarding the increases in the rates of morbidity and mortality that result from influenza and its complications. Although vaccination is the most important tool for preventing influenza, vaccination program among high-risk groups has not reached its predetermined aims in several settings. This study aimed to evaluate the impacts of clinical and demographic factors on vaccine compliance among the elderly in a setting that includes a well-established annual national influenza vaccination campaign. METHODS: This cross-sectional study included 134 elderly patients who were regularly followed in an academic medical institution and who were evaluated for their influenza vaccination uptake within the last five years; in addition, the demographic and clinical characteristics and the reasons for compliance or noncompliance with the vaccination program were investigated. RESULTS: In total, 67.1 percent of the participants received the seasonal influenza vaccine in 2009. Within this vaccinationcompliant group, the most common reason for vaccine uptake was the annual nationwide campaign (52.2 percent; 95 percent CI: 41.4-62.9 percent); compared to the noncompliant group, a higher percentage of compliant patients had been advised by their physician to take the vaccine (58.9 percent vs. 34.1 percent; p,0.01). CONCLUSION: The education of patients and health care professionals along with the implementation of immunization campaigns should be evaluated and considered by health authorities as essential for increasing the success rate of influenza vaccination compliance among the elderly.