Это не профилактика. Это снятие боли и давления. У нас в Украине ремантадин по цене около $2 за курс на 5 дней. В инструкции написано: раннее лечение и профилактика гриппа
Rimantadine (INN, sold under the trade name Flumadine) is an orally administered antiviral drug[1] used to treat, and in rare cases prevent, influenzavirus A infection. When taken within one to two days of developing symptoms, rimantadine can shorten the duration and moderate the severity of influenza. Both rimantadine and the similar drug amantadine are derivates of adamantane. Rimantadine was approved by the Food and Drug Administration (FDA) in 1994.
Rimantadine was approved for medical use in 1993.[2] 100% of seasonal H3N2 and 2009 pandemic flu samples tested have shown resistance to rimantadine and it is no longer recommended to prescribe for treatment of the flu.[3]