Before revision:  The optimal control strategies are categorized as ' suppression' and ' mitigation' strategies and are analyzed in both deterministic and stochastic models. In the stochastic model, vaccination at an uncertain time is taken into account .
After revision:  The optimal control strategies are categorized as ' suppression' and ' mitigation' strategies . We analyze how these strategies change when we incorporate vaccination into the model and find a new optimal `delay-mitigation' strategy .