Prognosis

Between November 2003 and July 2024, approximately 49% of patients with confirmed highly pathogenic avian influenza (HPAI) A(H5N1) virus infection reported to the World Health Organization have died.[37]​​ The case fatality rate is subject to selection bias as more severe/hospitalised cases are likely to be tested, and the true figure may be lower. Those who had progressive disease generally died from complications of acute respiratory distress syndrome (ARDS) and multi-organ failure. Early recognition of disease and early initiation of antiviral and supportive treatment may be associated with improved outcomes.[136][137]​​​ The presence of rhinorrhoea appears to indicate a better prognosis for children with HPAI A(H5N1) virus infection.[32]

HPAI 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.

No studies have assessed the long-term sequelae of infection among survivors, but most survivors had only mild disease. Long-term sequelae of ARDS include neuromuscular weakness, diminished lung function, post-traumatic stress disorder, and cognitive decline in older patients.[146][147]

Surviving patients may be immune to subsequent infection by antigenically similar HPAI A(H5N1) virus strains.

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