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

The immune response and serum nutritional status of 153 elderly residents of nursing homes (mean age 84.4 years) and 95 health care workers (mean age 36.8 years) were assessed before and after immunization with trivalent split-virus influenza vaccine. Postvaccination titers of hemagglutination inhibition (HAI) antibody to A/H1N1 and B among the elderly were lower than those among workers, but the seroconversion rates (greater than or equal to a four-fold rise) for A/H1N1 and A/H3N2 were unexpectedly higher among the elderly than among workers. However, the difference in the seroconversion rate for either strain between workers and the elderly disappeared after adjusting for the prevaccination HAI titer. Among all subjects, lower age and higher serum concentrations of total protein, albumin, Vitamin E and folate were associated with an intact immune response (postvaccination HAI titers >/=40 for at least one strain). In an age-adjusted analysis limited to the elderly, however, only Vitamin E showed a significant association with the immune response. These results suggested that Vitamin E may play an important role in maintaining the immune response, especially among the elderly.