Serological response to influenza vaccination and nutritional and functional status of patients in geriatric medical long-term care

Introduction: in the UK the Department of Health recommends influenza vacci nation for elderly people resident in institutional care. However the effic acy of vaccination may be reduced in very frail elderly people with functio nal impairment, undernutrition and multiple pathologies. Nutritional and fu nctional status is claimed to affect vaccine responses in healthy elderly s ubjects. We wished to determine if a relationship could be seen between nut ritional and functional status and seroconversion in patients receiving lon g- term care. Methods: all patients in geriatric medical long-term care were offered vacc ine. Consenting patients had pre- and pose-vaccine serology measured using single radial haemolysis. Anthropometry was measured to enable body mass in dex (BMI) to be calculated. Functional independence was assessed using the 20-point Barthel index. Results: of 260 patients who received influenza vaccine, 137 (36 male, 101 female) consented to venesection for serology and thus form the study popul ation. Mean age was 82 years (SD 7.9), The median Barthel score was 3/20 an d the mean BMI was 21.6 (SD 4.6, range 13-36.2). Antibodies to influenza A were undetectable both pre- and post-vaccination in 63/137 patients. In 49 patients the antibody titre rose after vaccination and 25 had detectable an tibody titres pre-vaccination which failed to rise past-vaccine. There were no significant associations between post-vaccination influenza antibody re sponses and BMI, Barthel score or age. Conclusion: frail elderly patients in geriatric medical long-term care had a poor antibody response to influenza vaccination. Within this group, serol ogical responses could not be predicted by nutritional or functional status .