Consider a cat owner (H) who owns a cat (K). Let:

C > 0 be the cost for H if H gets a common flu.

C_H > 0 be the cost for H to get human flu vaccination.

C_K > 0 be the cost for K to get cat's flu vaccination

Suppose that:

- probability of K getting the virus without vaccination = 1/2

- probability of K getting the virus with vaccination = (1/2)^2

- probability of H getting the virus without vaccination (in case K gets the virus) = 1/2

- probability of H getting the virus with vaccination (in case K gets the virus) = (1/2)^2

In the following the cat K plays the following game in proxy by H thus pay-off for K = pay-off for H.

We obtain the following pay-off table for this "game":

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