The severe case of H5N1 in Canada: more details
A new publication in The New England Journal of Medicine (NEJM) reports a case of critical illness caused by influenza A(H5N1) virus infection in a 13-year-old girl from British Columbia. She initially presented with conjunctivitis and fever and was discharged without treatment but later returned with respiratory distress and other severe symptoms.
Upon readmission, she was found to have a high viral load of influenza A, which necessitated her transfer to the pediatric intensive care unit. Despite treatment with oseltamivir and other antiviral medications, her condition worsened, requiring tracheal intubation and extracorporeal membrane oxygenation (ECMO).
The virus was identified as H5N1 clade 2.3.4.4b genotype D1.1, with mutations suggesting potential adaptation to human hosts. These mutations in the H5 hemagglutinin (HA) gene have previously been shown to enhance binding to α2-6–linked sialic acids, which act as receptors that facilitate viral entry into human respiratory cells and enable replication. This case underscores the severity of H5N1 infections in humans and raises concerns about the virus's ability to bind to human respiratory receptors, which could facilitate its spread and pose significant public health risks.
