http://repub.eur.nl/res/aut/31788/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/24597/ 2009-07-01T00:00:00Z Background: Disturbances in acquired immunity are considered to be responsible, at least in part, for the high infection rate and inadequate response to vaccinations observed in hemodialysis (HD) patients. The present prospective trial aimed to: (1) evaluate the immunogenicity of a standard influenza vaccine in HD patients, and (2) identify determinants of the immune response. Study Design: Prospective interventional open-label study. Setting & Participants: 201 long-term HD patients and 41 healthy volunteers. Intervention: Vaccination with a standard trivalent inactivated influenza vaccine. Outcomes: The primary outcome was seroprotection rate, defined as percentage of participants with an antibody titer of 40 or greater 1 month after vaccination. Measurements: All antibody titers were determined in duplicate by using the hemagglutination inhibition assay. Regression analyses were performed to investigate the association between demographics, uremic retention solutes (including p-cresol), inflammation, nutrition, iron status, trace elements, and immune response in HD patients. Results: More than 80% of HD patients showed seroprotection after vaccination. The immune response of HD patients was similar to that of healthy volunteers. Booster vaccination did not improve the immune response. High serum ferritin level was the only parameter independently associated with a better vaccination-induced antibody response in HD patients. Limitations: A high seroprotection rate at baseline undermined the power to identify clinical determinants of the immune response. Conclusions: Influenza vaccination is as efficacious in HD patients as in healthy volunteers. With the exception of serum ferritin, none of the investigated parameters of nutrition, inflammation, and dialysis adequacy had a significant impact on the immune response. Our data support annual vaccination of HD patients and question the clinical relevance of disturbances in acquired immunity in contemporary HD patients. http://repub.eur.nl/res/pub/30489/ 2008-02-01T00:00:00Z Whether influenza vaccination in solid-organ transplant recipients is efficacious remains a controversial issue. Furthermore, theoretical concerns have been raised regarding the safety of vaccination as it might trigger rejection of the allograft. The present prospective trial is aimed at investigating the antibody response and safety of influenza vaccination in renal transplant recipients (RTR). A total of 165 RTR and 41 healthy volunteers were vaccinated with a standard trivalent inactivated influenza vaccine. Hemagglutination-inhibiting (HI) antibodies were quantified before and 1 month after vaccination. Seroprotection (SP) and seroresponse (SR) were defined as a titer ≥40 and a 4-fold rise in HI titer, respectively. Similar SR rates were observed in both groups. Postvaccination SP rates in RTR amounted to 92.7%, 78.7% and 82.9% for A/H1N1, A/H3N2 and B, respectively. High baseline SP rates, most probably reflecting frequent preimmunizations, explain partly the high postvaccination SP rates. SR rate was independently and inversely associated with baseline SP rate. Mycophenolate mofetil (MMF) usage was associated with a 2.6-5-fold lower SR. Nonetheless, these patients showed good postvaccination SP rates. A booster dose did not enhance SP or SR rates. Influenza vaccination neither affected allograft function nor caused rejection episodes. In conclusion, influenza vaccination is efficacious and safe in renal transplantation.