The study findings suggested that zanamivir was also effective in this subgroup, but the sample size was too small to detect a statistically significant benefit. More data are needed to define clearly the role of the neuraminidase inhibitors in high-risk groups. Although not approved for prophylaxis, zanamivir and oseltamivir have also been shown to prevent influenza in healthy adults. Of note, Hayden and colleagues reported that 7 participants developed influenza within 2 weeks of completing the 6-week prophylaxis period, including 5 participants who had received oseltamivir. The neuramini-dase inhibitors may protect against illness only for as long as the medication is actually taken.
Immunization remains the mainstay of efforts for the prevention and control of influenza.
However, antiviral agents, including the neuraminidase inhibitors, are important adjuncts to vaccination for prevention and treatment during interpandemic periods for persons who have not been vaccinated, who develop influenza even if they have been vaccinated, and who travel between May and September to areas of the world with influenza activity. Decisions about which antiviral agent to use should be based on the relative importance of spectrum of activity, side effects, risk for emergence of resistance, and cost. Given the need to start treatment within 2 days of the onset of symptoms, providers will have to develop efficient processes for accurate diagnosis and timely prescribing of these agents if they are to be used widely. The antirivals will also play an important role during the next pandemic, providing critical protection during times when sufficient supplies of vaccine may not be available. Kristin L. Nichol, MD, MPH Veterans Affairs Medical Center Minneapolis, Minnesota, USA References 1.