Which antiviral is used for both preventing and treating influenza?

Oseltamivir is classified as a neuraminidase inhibitor and is effective for both the prevention and treatment of influenza. It works by inhibiting the function of the viral enzyme neuraminidase, which is necessary for the release of progeny influenza viruses from infected cells. By blocking this enzyme, Oseltamivir helps to reduce the spread of the virus within the respiratory tract, shortening the duration of flu symptoms and reducing the severity of the disease if administered early in the course of infection.

Moreover, Oseltamivir can be used prophylactically in individuals who have been exposed to the influenza virus to prevent the onset of the disease, making it a unique antiviral agent in its dual capacity for treatment and prevention. This aspect differentiates it from other antivirals listed; for example, Zanamivir is also a neuraminidase inhibitor but is primarily used for treatment, while Acyclovir and Ribavirin are indicated for different viral infections (herpes simplex viruses and hepatitis, respectively) and are not effective against influenza.