Seasonal IVIG contains high infectivity neutralizing and hemagglutination inhibition activity against seasonal flu virus strains selected for vaccines (2020-22)

IVIG solutions (10%) were tested for infectivity neutralization and hemagglutination inhibition against the influenza strains (two A and two B) recommended by the WHO for inclusion in vaccines for Northern and Southern hemispheres 2020-2022. The IVIG batches used were manufactured (June 2020) from plasma pools collected in the US. Potent neutralization and inhibition of hemagglutination were seen with these IVIG batches. This raises the possibility that IVIG could be added to existing therapies, especially in immunocompromised patients, to fight serious influenza infections. Further study of the potential of IVIG in influenza is warranted. ### Competing Interest Statement José María Díez, Daniel Casals, Carolina Romero and Rodrigo Gajardo are employees of Grifols.