Effect of sublingual administration of interferon-α on the immune response to influenza vaccination in institutionalized elderly individuals

A randomized double-blind placebo-controlled study was conducted to determine the effect of sublingual administration of IFNα on the immune response to influenza vaccination in elderly institutionalized individuals. Sublingual administration of 10 million IU of IFNα immediately prior to vaccination, reduced the geometric mean haemagglutination inhibitory (HAI) and IgG2 circulating antibody titers, and the secretory IgA (sIgA) response in saliva, to the New York strain of influenza A virus, 21 days post-vaccination, without detectable drug-related local or systemic toxicity. IFN treatment did not inhibit the immune response to the other components of the vaccine; the New Caledonia strain of influenza A virus, or the Jiangsu strain of influenza B virus. At the dose tested sublingual administration of IFNα reduces the immune response to influenza vaccination in elderly institutionalized individuals.