Immunogenicity of Three Different Influenza Vaccines against Homologous and Heterologous Strains in Nursing Home Elderly Residents

Table 2

Mean Fold Increase in titres (MFI), Seroprotection (≥40), and 4-fold increase rates according to viral strain and vaccine group.

Viral strain	Vaccine	MFI		After vaccination (%)
			Titre ≥ 40		4-fold
A/H1N1-like virus
A/Beijing/262/95
(Homologous)	Sub/MF59	8.7	100		94.4
	SVV	6.3	100		84.6
	Split	7.7	98.9		85.2
A/New Caledonia/20/99
(Heterologous)	Sub/MF59	6.1	87.5		68.1
	SVV	2.9	82.1		43.6
	Split	2.4	68.2		31.8
A/H3N2-like virus
A/Sydney/5/97
(Homologous)	Sub/MF59	5.5	77.8		76.4
	SVV	4.2	74.4		61.5
	Split	4.2	79.5		62.5
A/Wisconsin/67/2005
(Heterologous)	Sub/MF59	3.1	79.2		41.7
	SVV	2.0	56.4		22.9
	Split	2.0	78.4		27.3
B-like virus
B/Beijing/184/93
(Homologous)	Sub/MF59	3.8	100		66.7
	SVV	2.9	97.4		46.2
	Split	3.3	97.7		54.5
B/Malaysia/2506/2004
(Heterologous)	Sub/MF59	2.0	69.4		25.0
	SVV	1.5	71.8		7.7
	Split	1.9	73.9		26.1

∗P  <  .01; ∗∗P  <  .05.