XK and influenza: Because global surveillance of antiviral resistance is essential, the WHO Global Influenza Surveillance and Response System (GISRS) Expert Working Group for Surveillance of Antiviral Susceptibility (WHO-AVWG) has been conducting a global analysis of circulating influenza A and B viruses for NA inhibitor and baloxavir susceptibilities by using a combination of phenotypic methods analyzing antiviral susceptibility and genotypic methods detecting amino acid substitutions associated with antiviral resistance [9].