Haemagglutinin antigenic site differences in circulating H3N2 viruses relative to the 2012–13 egg-adapted A/Victoria/361/2011 IVR-165a high growth reassortant vaccine strain.

N = number of sentinel viruses with that sequence. Bold font signifies amino acid (AA) substitutions compared with IVR-165. Clade designation, number of antigenic site differences and percent antigenic site pairwise identity are also displayed. Only the 31/131 antigenic site positions showing differences between circulating H3N2 viruses and IVR-165 are displayed. AA sequences at those positions for other recent vaccine viruses are also displayed.a. IVR-165 is the egg-adapted high growth reassortant strain substituted by manufacturers for the MDCK-passaged A/Victoria/361/2011 (H3N2) prototype virus recommended as 2012–13 vaccine component by the World Health Organization (WHO) designated here as A/Victoria/361/2011 (MDCK).b. Number of antigenic site AA differences and percent antigenic site identity relative to IVR-165. Percent identity derived as per Text S1.c. A/Victoria/210/2009 (X-187) is the egg-adapted high growth reassortant strain used by manufacturers for the 2011–12 influenza vaccine for the northern hemisphere., shown for historic comparison.d. A/Texas/50/2012 (MDCK) and (X-223) are the WHO-recommended prototype and egg-adapted high growth reassortant strains, respectively, for the 2013–14 influenza vaccine for the northern hemisphere, shown for added comparison.