Seasonal Influenza Vaccine and Avian Influenza

Seasonal Influenza Vaccine and Avian Influenza
Sporadic human cases of infection with highly pathogenic avian influenza A (H5N1) viruses have been identified in Asia, Africa, and the Middle East, primarily among persons who have had close contact with sick or dead birds (356-361). To date, no evidence exists of genetic reassortment between human influenza A and H5N1 viruses. However, influenza viruses derived from strains currently circulating in animals (e.g., the H5N1 viruses that have caused outbreaks of avian influenza and occasionally have infected humans) have the potential to recombine with human influenza A viruses (362,363).

To date, highly pathogenic H5N1 influenza viruses have not been identified in wild or domestic birds or in humans in the United States. Current seasonal influenza vaccines provide no protection against human infection with avian influenza A viruses, including H5N1. However, reducing seasonal influenza risk through influenza vaccination of persons who might be exposed to nonhuman influenza viruses (e.g., H5N1 viruses) might reduce the theoretical risk for recombination of an avian influenza A virus and a human influenza A virus by preventing seasonal influenza virus infection within a human host. CDC has recommended that persons who are charged with responding to avian influenza outbreaks among poultry receive seasonal influenza vaccination (364). As part of preparedness activities, the Occupational Safety and Health Administration (OSHA) has issued an advisory notice regarding poultry worker safety that is intended for implementation in the event of a suspected or confirmed avian flu outbreak at a poultry facility in the United States. OSHA guidelines recommend that poultry workers in an involved facility receive vaccination against seasonal influenza; OSHA also has recommended that HCP involved in the care of patients with documented or suspected AI should be vaccinated with the most recent seasonal human influenza vaccine to reduce the risk for co-infection with human influenza A viruses (365). Human infection with novel influenza A virus strains, including influenza A viruses that cause avian influenza, is now a nationally notifiable disease (366).

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