Potential antigenic mismatch of the H3N2 component of the 2019 Southern Hemisphere influenza vaccine

Here, we find that the egg-adapted H3N2 component of the 2019 Southern Hemisphere influenza vaccine elicits an antibody response in ferrets that is highly focused on antigenic site A of hemagglutinin. This is potentially problematic since most H3N2 viruses currently circulating in the Southern Hemisphere possess antigenic site A substitutions.