Five influenza viruses from birds (H5N1, H7N7, H7N2, H7N3 and H9N2) have been the cause of human infections during the last decade. Of these H5N1 infections have been the worst with high mortality.
Until now, H5N1 infections have been seen among the poultry farm workers or their immediate family members only. Fortunately, unlike other human influenza viruses (H1N1, H2N2 H3N2), this virus has not been able to adapt itself for efficient human to human transmission so far. God forbids if it gets that property, no age group will be spared.
Other influenza virus vaccines do not afford any protection against this infection. Tamiflu (neuramindase inhibitor) does protect exposed individuals. However, tamiflu resistant viruses have been isolated recently from Vietnam.