WHO Issues Guidelines for Antiviral Treatment of H1N1 and Other Influenza

August 27, 2009 — The World Health Organization (WHO) has issued guidelines for antiviral treatment of
novel influenza A (H1N1) and other influenza. The purpose of the new recommendations, which were posted online
August 20, is to provide a basis for advice to clinicians regarding the use of the currently available antivirals for
patients presenting with illness caused by influenza virus infection, as well as considerations
regarding potential use of these antiviral medications for chemoprophylaxis.

On the basis of a review of data collected with previously circulating strains, and treatment of human
H5N1 influenza virus infections, the new guidelines expand on recommendations published in May 2009
, titled "Clinical management of human infection with new influenza A (H1N1) virus: Initial guidance."
These new guidelines do not change recommendations in the WHO rapid advice guidelines on
pharmacological management of humans infected with highly pathogenic avian influenza A (H5N1) virus.

"In April 2009, the [WHO] received reports of sustained person to person infections with [H1N1]
virus in Mexico and the United States," write Edgar Bautista, from Médico Neumólogo Intensivista, Jefe
de UCI-INER in Mexico, and colleagues. "Subsequent international spread led WHO to declare on 11 June 2009
that the first influenza pandemic in 41 years had occurred. This 2009 pandemic H1N1 influenza virus has now spread
worldwide, with confirmed cases of pandemic H1N1 virus infection reported in more than 100 countries in all 6 WHO regions[, which] has
led to the need to add to the existing guidance on the use of antivirals."

The new recommendations highlight oseltamivir and zanamivir, which are neuraminidase inhibitors, and amantadine
and rimantadine, which are M2 inhibitors. Suggestions are also provided regarding the use of some
other potential pharmacological treatments, such as ribavirin, interferons, immunoglobulins, and corticosteroids.

Management of patients with pandemic influenza (H1N1) 2009 virus infection is the primary focus of the statement,
although it also includes guidance regarding the use of the antivirals for treatment of other seasonal influenza virus
strains, as well as for infections resulting from novel influenza A virus strains.

The guidelines urge country and local public health authorities to issue local recommendations for clinicians
periodically, based on epidemiological and antiviral susceptibility data on the locally circulating influenza
strains. As the prevalence and severity of the current pandemic evolves, WHO anticipates that additional data
will be forthcoming that may require revision of the current recommendations. WHO therefore plans to review
the guidance no later than September 2009 to determine whether modifications to the recommendations are needed