The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 11 No. 3 • May 2008

Seasonal Flu Shots May Protect Against Bird Flu

Good news for anyone concerned about bird flu: a recent paper1 reports finding cross-reactivity between human and avian influenza strains in some healthy donors recently vaccinated against seasonal influenza. What this means is that there may be increased immune response to bird flu in people who received seasonal flu shots recently.

The researchers evaluated cell-mediated immunity in 42 healthcare workers at the Spallanzani Institute (Rome, Italy) who wished to receive seasonal flu shots. Peripheral blood mononuclear cells (PBMC) were isolated from each subject’s blood and were stimulated with the influenza vaccine preparation, UV-inactivated bird influenza, or synthetic influenza (of the bird flu variety) peptides for 3 days and then expanded for 6 more days in the presence of IL-2 (a cell-mediated immunity factor). What they found was that six donors had a “noteworthy” increase of IFN-gamma-producing CD4 T cells specific for avian influenza as compared to baseline levels. Three other donors had “an increased frequency of H5NI [bird flu strain] peptides-specific CD4 T cell even if they were unable to respond to whole virus.”

Seasonal vaccination also affected humoral (B-cell) immunity. “A 4-fold rise of HA [hemagglutinin] antibody titer is considered noteworthy, and after vaccination most donors (28/38, 73.7%) showed a noteworthy rise of HI [a subtype strain of influenza] titers against vaccine preparation . . .” The authors concluded that “Our findings indicate that seasonal vaccination can raise neutralizing immunity against influenza (H5N1) . . .” thereby “showing the existence of an antibody-dependent cross-type immunity.”


  1. Gioia et al. Cross-subtype immunity against avian influenza in persons recently vaccinated for influenza. Emerging Infect Dis 14(1):121-8 (2008).

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