Which antiviral is effective against both influenza A and B?

• A. Oseltamivir (Tamiflu)
• B. Acyclovir
• C. Fluconazole
• D. Nystatin

Answer: (A)

Key idea: neuraminidase inhibition stops the influenza virus from spreading from infected cells, and this applies to both major influenza types.

Oseltamivir works by blocking neuraminidase, an enzyme on the surface of influenza viruses that helps release new viral particles from infected cells and promotes spread in the respiratory tract. By inhibiting this enzyme, oseltamivir prevents release and limits propagation of both influenza A and influenza B, making it effective for treating and, in some cases, preventing illness from either strain. It’s given orally as a prodrug that becomes the active form in the body, and starting treatment within about 48 hours of symptoms typically shortens the illness and can reduce complications in at-risk individuals.

Acyclovir targets herpesviruses, not influenza. Fluconazole and nystatin are antifungals, not antivirals against influenza.