The influenza vaccine can give humans some protection against the avian flu.

• A. True
• B. False
• C. Not sure
• D. Sometimes

Answer: (B)

Vaccines are effective when the immune response they provoke targets the same viral antigens that people are exposed to. Seasonal influenza vaccines are formulated to match the influenza A and B strains that are predicted to circulate in humans that year. Avian influenza viruses, like H5N1 or H7N9, are antigenically different from those human strains. The antibodies produced by the seasonal vaccine mainly recognize the included human strains, so they do not reliably protect against avian strains. There can be some rare, limited cross-reactivity, but it isn’t dependable protection. So, the seasonal flu vaccine does not reliably provide protection against avian influenza.