From bench to bedside and back: the SENIEUR Protocol and the efficacy of influenza vaccination in the elderly

Prophylaxis with vaccines is important in geriatrics as, apart from specific protection, it reduces incidence of potentially fatal infectious complications and exacerbations of existing medical conditions. Post-vaccination protection depends on immunity and therefore markers of immune status could be used to predict efficacy of vaccination. From the practical point of view, the determination of simple and robust methods for assessing immunity, which could enable practitioners to distinguish patients at risk of vaccination unresponsiveness, is desirable. Additional care, necessary to avoid possible complications, could be then targeted to such patients. Here, we discuss correlations between immune parameters and the clinical status of elderly people challenged with anti-influenza vaccination and ways to classify immune status, based on results obtained between 1999 and 2004 in the elderly immunized annually against influenza. These studies document a correlation between health status assessed according to the SENIEUR Protocol and response to the vaccination. Patients classified as SENIEUR-compatible responded to the vaccine, while non-SENIEURs did not. Factors most strongly associated with unresponsiveness were, perhaps unexpectedly, circulatory and psychiatric diseases, although both humoral and cellular immune responsiveness did correlate with levels of proinflammatory cytokines in the serum. Patients whose humoral responses improved during subsequent immunizations were characterized by well-preserved natural killer (NK)-mediated cytotoxicity. In contrast to the first-immunization responders, the second- immunization responders were characterized by elevated levels of proinflammatory cytokines and Cytomegalovirus seropositivity, which placed them in the non-SENIEUR group, although they were not yet frail and still lived independently. From this series, we conclude that detailed clinical data together with some simple markers such as IL 6 levels seem sufficient to provide clinicians with presumptive information on the condition of the immune system and to allow for initial prediction of vaccination efficiency. Those patients predicted to respond poorly could be considered for alternative treatment.