Table 1. Demographics of the enrolled volunteers.

Number of males / females (total)	3/20 (23)
Age range	25–64 y
Mean age	50.2 y
Received seasonal influenza vaccine in 2009*	8 (34.8%)
Received previous seasonal influenza vaccine*	18 (78.3%)
Experienced influenza symptoms past year*	4 (17.4%)
Received anti influenza drugs during trial*	2 (8.7%)1
Underlying disease*	2 (8.7%)2

^*Data presented as number of subjects reporting each variable.

¹ Both reported taking prophylactic Tamiflu.

² Both reported underlying respiratory disease.