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 vaccination for elderly people resident in institutional care. However the efficacy of vaccination may be reduced in very frail elderly people with functional impairment, undernutrition and multiple pathologies. Nutritional and functional status is claimed to affect vaccine responses in healthy elderly subjects. We wished to determine if a relationship could be seen between nutritional and functional status and seroconversion in patients receiving long- term care. Methods: all patients in geriatric medical long-term care were offered vaccine. Consenting patients had pre- and pose-vaccine serology measured using single radial haemolysis. Anthropometry was measured to enable body mass index (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 population. Mean age was 82 years (SD 7.9), The median Barthel score was 3/20 and 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 antibody titres pre-vaccination which failed to rise past-vaccine. There were no significant associations between post-vaccination influenza antibody responses 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, serological responses could not be predicted by nutritional or functional status.