Immune efficacy of first and repeat trivalent influenza vaccine in healthy subjects and hemodialysis patients.

Influenza vaccination is recommended to patients from groups at risk and to healthy persons alike. It is not completely clear whether persons vaccinated every year benefit more from the vaccination in any given season in comparison with those who are vaccinated for the first time. The aim of the study was to analyze whether influenza vaccination in previous seasons influences the response to ongoing vaccination in the healthy population and in hemodialyzed patients. The outcome measure was the production of anti-hemagglutinin antibodies in 71 hemodialyzed patients (Group A) and 63 patients of primary healthcare clinic, without chronic renal failure (Group B). The patients of these two groups were subdivided into never vaccinated before and previously vaccinated against influenza. After the current vaccination, significantly lower levels of anti-A/H1N1/ antibodies were found in the hemodialyzed compared with non-hemodialyzed previously vaccinated, but not unvaccinated, patients. The hemodialyzed patients, previously unvaccinated, had at baseline significantly lower levels of anti-A/H3N2/ and anti-B antibodies than those who were previously vaccinated; the differences were no longer significant after the current vaccination. We conclude that although antiflu immunization in previous seasons leads to higher baseline antibody titers in hemodialysis compromised patients, which is less evident in non-hemodialyzed patients, it is of little influence on the immunoresponse to current influenza vaccination, in both hemodialyzed and non-hemodialyzed patients.