In this study they found that horse-radish inhibits the H1N1 strain of the swine flu and that the addition of caffeine resulted in a synergistic effect which further lowered mortality rates from this virus.
 
Therefore, its cheap sushi restaurant time. You get your green tea and horse-radish (real wasabi is served only in the fine japanese restaurants, the rest are cheap (but anti-viral) horseradish). However we recommend you stick with vegetable rolls or california or other cooked rolls since who knows what else you might contract from raw fish at a cheap sushi restaurant.
 
Virologie. 1985 Apr-Jun;36(2):95-8.Links