Operational guidance for sharing seasonal influenza viruses with WHO Collaborating Centres (CCs) under the Global Influenza Surveillance and Response System (GISRS)

The procedure defines the functions of National Influenza Centers (NICs) within the Global Influenza Surveillance and Response System (GISRS), focusing on the timely shipment of seasonal influenza viruses to WHO Collaborating Centers (CCs) for detailed antigenic and genetic characterization. NICs select and submit a subset of positive clinical samples or representative virus isolates collected in the last 4 to 8 weeks, prioritizing viruses whose subtype cannot be determined, clinically significant cases, or unusual outbreaks.

This procedure allows for monitoring the evolution of influenza viruses, supporting the selection of vaccine strains, evaluating sensitivity to antivirals, and strengthening global surveillance and emergency and pandemic response capacity. Timely shipment is essential for the data generated by the CCs to be incorporated into the WHO's biannual recommendations on the composition of influenza vaccines. For more information: laboratoryresponse@paho.org