Immune response to influenza vaccine in the elderly: association with nutritional and physical status.

Aim: To investigate the distribution of hemagglutination inhibition (HI) titers before and after influenza vaccination and to examine the relationship between physical and nutritional factors and the change in HI titer after influenza vaccination in the elderly.

Methods: Pre-post-vaccination HI titers were determined from 203 individuals aged 65 years or older residing in a nursing home. For the assessment of physical and nutritional status, information was retrieved from care records.

Results: The immune response to vaccination was assessed as good in 122 subjects based on a fourfold rise or more in HI titer after vaccination for at least one of three vaccine strains. In univariate logistic regression analysis with poor versus good immune response as the dependent variable, factors found to be significantly associated with a poor immune response were disability, a combination of body mass index less than 18.5 and bodyweight loss in 6 months or 5% or more, mid-upper-arm circumference of less than 80%, arm muscle circumference of less than 80% and total protein of less than 6.5 g/dL. Physical and nutritional indicators might be useful in identifying individuals who are unlikely to have a good immune response to influenza vaccination. In a multivariate analysis, the association remained significant for a low level of activities of daily living and a combination of body mass index of less than 18.5 and bodyweight loss in 6 months of 5% or more.

Conclusion: Elderly individuals with poor physical and nutritional status tended to respond poorly to influenza vaccination. A low level of activities of daily living and a combination of being underweight and having had recent bodyweight loss are good indicators of a poor immune response.