Which antivirals shorten the course of influenza A or B?

• A. Zanamivir and Oseltamivir shorten the course of influenza A or B
• B. Rimantadine and Amantadine shorten influenza A only
• C. Amantadine shorten influenza B only
• D. Rimantadine shorten influenza B only

Answer: (A)

The main idea is understanding which antivirals shorten illness duration for influenza and their activity against different virus types. Neuraminidase inhibitors, namely oseltamivir and zanamivir, shorten the course of illness for both influenza A and influenza B when started within about 48 hours of symptom onset. They work by blocking the neuraminidase enzyme, which is needed for viral release from infected cells, thereby reducing viral spread and the duration of symptoms.

In contrast, the older adamantane drugs, amantadine and rimantadine, target the M2 ion channel and are effective mainly against influenza A; resistance among circulating strains is common, and they do not reliably shorten illness caused by influenza B. That’s why those drugs aren’t considered to shorten the course of influenza B.

So, the choice that states zanamivir and oseltamivir shorten the course of influenza A or B reflects the correct concept: neuraminidase inhibitors shorten illness for both A and B.