When do you take Tamiflu?

Tamiflu used as a prophylactic (preventive) measure for the flu is usually prescribed for ten days following the last known or suspected exposure to the virus. If it is being used to treat an already infected person to lesson the severity of symptoms and shorten the duration of the flu symptoms, it is usually prescribed for a period of five days.

It does not provide long term protection from the flu. Only an immunization (vaccine) can do that.