Figure 1: Genetic characterization of viruses collected in
season 2019-2020 (log2 HI titre reciprocal = HIU,
hemagglutination inhibiting units log2). (A)
A(H1N1)pdm09 viruses, (B) A/(H3N2) viruses); (C) B/Victoria viruses; (D)
B/Yamagata viruses. Hemagglutination inhibition was performed using
ferret antisera against A/Brisbane/02/2018 [ A(H1N1)pdm09 ],
A/Kansas/14/2017 [ A/(H3N2) ], B/Colorado/6/2017 (B/Victoria) and
B/Phuket/3073/2013 (B/Yamagata). Note that there was a good coverages of
vaccine viruses in the influenza season 2019-2020 with the exception of
N156K viruses.
Each rhombus represents a virus. Dark blue column, variation of the
positive control (vaccine virus) = 1 log2; light blue
column, accepted tolerance in antigenic variation against vaccine
viruses = 2 log2; dark red column, viruses with N156K
substitution in HA.