Table 6. Cross-reactive HI and neutralizing antibody responses to A/Sydney virus after two doses of the A/Victoria vaccine.

Item	Antibody responses	Week	Seruma	Nasal washb
GMT (Mean geometric increase)	HI antibody	0	21.2 (1.00)	13.6 (1.00)
		6	30.5 (1.44)	22.2 (1.63)
	Neutralizing antibody	0	160.0 (1.00)	23.0 (1.00)
		6	233.2 (1.46)	48.7 (2.12)

^a Serum HI and neutralization titers of < 1:10 were considered negative and arbitrarily assigned a titer of 1:5. ^b Nasal wash HI and neutralization titers were determined using concentrated nasal wash samples containing 1 mg/ml total protein. Nasal HI and neutralization titers of < 1:20 were considered negative and arbitrarily assigned a titer of 1:10.