Table 3. Serum neutralizing antibody responses after two doses of the nasal vaccine.

	Time after first vaccination (week)	Serum a
GMT (Mean geometric increase)	0	28.7 (1.00)
	6	229.7 (8.00)
Conversion rate or significant increase in titer [n/N (%, 95% CI)] b	6	29/46 (63.0, 48.5–77.6)
Protection rate [n/N (%, 95% CI)] b	0	14/46 (30.4, 16.6–44.3)
	6	40/46 (87.0, 76.8–97.1)

^a Serum NT titers of <1:10 were considered negative and were arbitrarily assigned a titer of 1:5. ^b Conversion rate and protection rate were tentatively estimated by correcting for the relative ratio between GMT of NT titers and that of HI titers; a serum NT titer of 1:80 was considered to be a 1:40 of the lowest protection level in HI titers.