Avian influenza A (H5N1) virus infection is an acute infectious disease. Patients may experience prolonged virus replication and viral shedding, and their hospital course may last up to 3 weeks or longer after disease onset. Once surviving patients have clinically improved and have been discharged, they may be immune to subsequent infection by antigenically similar highly pathogenic avian influenza (HPAI) H5N1 virus strains.
Close observation and postexposure oseltamivir or zanamivir chemoprophylaxis is recommended for healthcare workers after unprotected close exposure to a symptomatic, suspected, or confirmed HPAI H5N1 case (within 2 m) in the healthcare setting, as well as for household and close contacts of a patient with suspected or confirmed HPAI H5N1 virus infection.
Suspected cases should be reported immediately to public health authorities, who will assist with diagnostic evaluation, case management, and contact investigation.
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