TABLE 2.

Survival following challenge of C57BL/6 mice vaccinated with SSW202, by size of challenge dose, number of vaccine inoculations, and time between last vaccination and challenge

Immunization dose (CFUsa)	Challenge dose (CFUs)b	No. of vaccina-tions	Time to challenge (days)c	No. of mice	% Sur-vival	P valued
1 × 107–2 × 107	1 × 107–2 × 107	2	21	15	93	n/ae
Saline	1 × 107–2 × 107	2	21	16	0	<0.0001
1 × 107–2 × 107	1 × 107–2 × 107	1	21	11	91	0.82
1 × 105–2 × 105	1 × 107–2 × 107	2	21	6	50	0.053
1 × 106–2 × 106	1 × 107–2 × 107	2	21	5	60	0.14
1 × 107–2 × 107	5 × 107	2	21	5	40	0.032
1 × 107–2 × 107	1 × 108–2 × 108	2	21	5	40	0.032
1 × 107–2 × 107	1 × 107–2 × 107	2	45–49	10	60	0.12

^aVaccination was performed by the intranasal route. 

^bChallenge was by the intranasal route using wild-type strain 2457T. 

^cNumber of days between last vaccination and challenge. 

^dP value was calculated using the Fisher’s exact test of percent survival versus that of mice immunized twice with 1 × 10⁷ to 2 × 10⁷ SSW202 and challenged with 1 × 10⁷ to 2 × 10⁷ 2457T (first line). 

^en/a, not applicable.