The use of antiviral drugs for the treatment of people presenting with symptoms is unlikely to be the most suitable approach during a seasonal outbreak. This is the conclusion of a study published Online First and in an upcoming edition of The Lancet Infectious Diseases. The review is the work of Dr Jane Burch and Professor Lesley Stewart, Centre for Reviews and Dissemination, University of York, UK, and collaborators. It reports that the amplification of the vaccination policy could result in a more clinically efficient and cost-effective strategy. But the cost-effectiveness of this is yet to be proven.

The authors mention that the findings could have significance for the current H1N1 pandemic, although the review used data for seasonal flu. They worked on a meta-analysis of the efficacy of the antiviral treatments: oseltamivir (tamiflu) and zanamivir (relenza). Healthy adults without known underlying health problems were included in the study. They also assessed individuals at risk of flu related complications, such as people with lung or heart disease, diabetes, or other health problems. In healthy adults, tamiflu reduced the median time to symptom alleviation by 0.55 days and relenza by 0.57 days. For at-risk groups, the corresponding reductions were 0.74 days (tamiflu) and 0.98 days (relenza). These reductions in symptoms are somewhat small in the perspective of the whole length of symptoms for most patients. Also, there was little information available on the occurrence of complications.

Instead of treating individuals when they present influenza symptoms, some different strategies might be more clinically efficient and cost effective. These include:

• Vaccination.
• Post-exposure prophylaxis: treating people with antiviral drugs after they have been in contact with flu.
• Expectant treatment: people that have been in contact with influenza are prescribed antiviral drugs to be taken as and when symptoms present.
• Making the drugs available over the counter for purchase.
• Introduction of rapid testing in the family doctor’s consulting room before prescription, in order to allow the treatment only of people who have flu.

Each of these options has advantages and disadvantages. However, the authors explain: “Any strategy that increases the availability of the drugs to the general public, consequently increasing the rates of inappropriate use, could increase the chances of viral strains developing resistance.”

They write in conclusion: “Although the evidence for clinical effectiveness in healthy and at-risk populations is similar, and the data relating to complications is lacking in both groups, it is reasonable to recommend precautionary treatment to people who are at an increased risk of suffering influenza-related complications. Even if active management of seasonal influenza in healthy adults is deemed a public health priority, recommending the use of antiviral drugs for the treatment of people presenting with symptoms is unlikely to be the most appropriate course of action, given the high specificity of zanamivir and oseltamivir to the influenza virus, and the debatable clinical importance of their affect on symptom duration. Extension of the vaccination policy might be a more appropriate choice for healthy adults, and an assessment of cost-effectiveness that includes societal costs of extending the UK vaccination policy to all working-age adults seems desirable.”

“Prescription of anti-influenza drugs for healthy adults: a systematic review and meta-analysis”
Jane Burch, Mark Corbett, Christian Stock, Karl Nicholson, Alex J Elliot, Steven Duffy, Marie Westwood, Stephen Palmer, Lesley Stewart
DOI: 10.1016/S1473-3099(09)70199-9
The Lancet Infectious Diseases

Written by Stephanie Brunner (B.A.)