What antiviral treatments are recommended for influenza, and when should they be initiated?

Recommended antiviral treatments for influenza include oral oseltamivir and inhaled zanamivir. Oseltamivir is generally the first-line treatment for most patients, especially those in 'at risk' groups, while zanamivir is preferred in cases where oseltamivir resistance is a concern, such as in severely immunosuppressed patients infected with influenza A(H1N1) strains known for higher oseltamivir resistance ¹.

Timing of initiation is critical: antiviral treatment should ideally be started within 48 hours of symptom onset (36 hours for zanamivir in children) to maximize efficacy. Starting treatment beyond these time frames is considered off-label and requires clinical judgment ¹.

Antiviral treatment is recommended for people with influenza if all the following apply: influenza is circulating in the community as indicated by national surveillance; the person belongs to an 'at risk' group (including those aged over 65, children under 6 months, pregnant women, and people with chronic respiratory disease, asplenia, or immunosuppression); and treatment can be started promptly within the specified time window ¹.

For previously healthy individuals not in an 'at risk' group but at serious risk of complications, oral oseltamivir may be considered if treatment can start within 48 hours of symptom onset ¹.

In severely immunosuppressed patients, choice of antiviral depends on the circulating influenza strain: oseltamivir is used for strains with lower resistance risk (e.g., A(H3N2), influenza B), while zanamivir is preferred for higher resistance risk strains (e.g., A(H1N1)) ¹.

Antiviral treatment should not be delayed awaiting laboratory confirmation of influenza; clinical diagnosis supported by epidemiological context is sufficient to initiate treatment ¹.

Supportive care including adequate hydration, symptomatic relief with paracetamol or ibuprofen, and rest is advised alongside antiviral therapy ¹.

Recent literature in oncology patients highlights the importance of early antiviral treatment in immunocompromised populations to reduce influenza-related complications and mortality, reinforcing guideline recommendations for prompt initiation in high-risk groups (El Ramahi and Freifeld, 2019).