A study published Online First and in the September edition of the Lancet Infectious Diseases concludes that the use of antiviral drugs for the treatment of people presenting with symptoms is unlikely to be the most appropriate course of action during a seasonal outbreak. The extension of the vaccination policy could be a more clinically effective and cost-effective strategy, but the cost-effectiveness of this is yet to be established. The Review is written by Dr Jane Burch and Professor Lesley Stewart, Centre for Reviews and Dissemination ,University of York, UK, and colleagues.
Although the Review is based on data for seasonal flu, the authors say the findings could have relevance for the current H1N1 pandemic. They did a meta-analysis on the effectiveness of the antiviral treatments oseltamivir (tamiflu) and zanamivir (relenza). The study assessed both healthy adults (those without known underlying health problems) and those at risk of flu related complications (eg, 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 relatively small in the context of the overall length of symptoms for most patients. Little information was available on the incidence of complications.
Several other approaches might be more effective clinically, and in terms of cost, than treating individuals when they present with influenza symptoms. These include vaccination, postexposure 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, and the introduction of rapid testing in the family doctor surgery before prescription (to allow the treatment only of people who have flu). There would be advantages and disadvantages to each of these options. However, the authors say: "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 conclude: "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."
For Dr Jane Burch and Professor Lesley Stewart, Centre for Reviews and Dissemination University of York, UK, please contact Paul Wilson, Centre for Reviews and Dissemination Press Office T) +44 (0)1904 321073 E) pmw7@york.ac.uk / jb67@york.ac.uk / ls536@york.ac.uk
For full Review, see: http://press.thelancet.com/tlidantivirals.pdf
Notes to editors: *Healthy adults: Range of symptom duration for zanamivir trials: Placebo 4.5 to 6.5 days, zanamivir, 3.5 to 5.0 days; Range for oseltamivir trials: Placebo: 3.7 to 4.8 days oseltamivir: 3.1 to 4.1 days At-risk groups: Range of symptom durationfor zanamivir trials: Placebo: 5.8 to 11.5 days, zanamivir: 3.75 to 9.0 days. Range for oseltamivir trials: placebo: 5.8 to 6.8 days, oseltamivir: 4.9 to 6.0 days.
Journal
The Lancet Infectious Diseases