Lack of correlation between nutritional status and seroprotection against influenza in a long term care facility.

We conducted a prospective study in a long-term care facility. Virologic diagnosis was assessed using viral isolation, polymerase chain reaction and serology for all patients with a flu-like syndrome. Albumin, vitamins and trace elements were also measured. Results. The risk of influenza increased 6.5-fold in patients with an antibody titer of 40 during the influenza outbreak (P = 0.04). Micronutriments and vitamins deficiencies were important. Patients with antibody titer > 1:40 could still be infected by the virus without correlation with the nutritional status. Conclusion. Humoral protection with a titer > 1:40 might not be protective in the elderly. Nutritional deficiencies were too prevalent to detect any effect on the results.