WHO issue antiviral flu recommendations

Published 21 August 2009

The World Health Organization issued recommendations for antiviral treatment of both seasonal and swine flu; the guidelines represent the consensus reached by an international panel of experts who reviewed all available studies on the safety and effectiveness of these drugs

The World Health Organization (WHO) has today issued guidelines for the use of antivirals in the management of patients infected with the H1N1 pandemic virus. The guidelines represent the consensus reached by an international panel of experts who reviewed all available studies on the safety and effectiveness of these drugs. Emphasis was placed on the use of oseltamivir and zanamivir to prevent severe illness and deaths, reduce the need for hospitalization, and reduce the duration of hospital stays.

The pandemic virus is currently susceptible to both of these drugs (known as neuraminidase inhibitors), but resistant to a second class of antivirals (the M2 inhibitors).

Worldwide, most patients infected with the pandemic virus continue to experience typical influenza symptoms and fully recover within a week, even without any form of medical treatment. Healthy patients with uncomplicated illness need not be treated with antivirals. On an individual patient basis, initial treatment decisions should be based on clinical assessment and knowledge about the presence of the virus in the community.

In areas where the virus is circulating widely in the community, clinicians seeing patients with influenza-like illness should assume that the pandemic virus is the cause. Treatment decisions should not wait for laboratory confirmation of H1N1 infection.

This recommendation is supported by reports, from all outbreak sites, that the H1N1 virus rapidly becomes the dominant strain.

Treat serious cases immediately
Evidence reviewed by the panel indicates that oseltamivir, when properly prescribed, can significantly reduce the risk of pneumonia (a leading cause of death for both pandemic and seasonal influenza) and the need for hospitalization.

For patients who initially present with severe illness or whose condition begins to deteriorate, WHO recommends treatment with oseltamivir as soon as possible. Studies show that early treatment, preferably within 48 hours after symptom onset, is strongly associated with better clinical outcome. For patients with severe or deteriorating illness, treatment should be provided even if started later. Where oseltamivir is unavailable or cannot be used for any reason, zanamivir may be given.

This recommendation applies to all patient groups, including pregnant women, and all age groups, including young children and infants.

For patients with underlying medical conditions that increase the risk of more severe disease, WHO recommends treatment with either oseltamivir or zanamivir. These patients should also receive treatment as soon as possible after symptom onset, without waiting for the results of laboratory tests.

As pregnant women are included among groups at increased risk, WHO recommends that pregnant women