Table 2.

Hemagglutination inhibition (HI) titers of ferret sera against A(H1N1)pdm09 viruses.

Vaccine Strain:		Ferret ID Immunized against:
		Singapore a		WD039-0 b		GR156 e		GR253 f
		111	112	121	122	131	132	141	142
2017–2019 season	Singapore a	2048	1024	1024	2048	1024	4096	64	64
2018–2019 season	WD039-0 b	1024	1024	2048	2048	1024	2048	128	128
	BB251 c	2048	1024	2048	4096	1024	2048	128	128
2019–2020 season	BB262 d	1024	1024	2048	2048	2048	2048	16	32
	GR156 e	1024	1024	2048	4096	1024	2048	16	32
	GR253 f	16	16	32	64	16	32	512	1024
	AC109 g	32	32	64	128	32	64	1024	4096

^a A/Singapore/GP1908/2015, ^b A/Tokyo/UT-WD039-0/2019, ^c A/Tokyo/UT-BB251/2019, ^d A/Tokyo/UT-BB262/2019, ^e A/Tokyo/UT-GR156/2019, ^f A/Tokyo/UT-GR253/2020, and ^g A/Tokyo/UT-AC109/2020 were used. Boldface type indicates homologous combinations.