New Guidelines on H1N1 Influenza Advise Quicker Use of Antivirals

Updated treatment guidelines for H1N1 influenza released by the World Health Organization (WHO; Geneva, Switzerland) urge clinicians to administer antiviral medications to patients in at-risk groups as soon as they experience flu symptoms.

At-risk groups include patients with pneumonia, those with uncomplicated influenza-like illness that worsens or fails to improve within 72 hours, pregnant women, children younger than two years, and individuals with chronic illnesses such as respiratory problems. The updated guidelines also state that clinicians should not delay antiviral treatment for patients with suspected H1N1 influenza for the sake of conducting tests to confirm the diagnosis. In addition, a negative result from some rapid influenza diagnostic tests should not justify withholding antiviral therapy since these tests miss many infections with pandemic H1N1 virus.

The updated WHO guidelines specify watchful waiting for 72 hours for patients who have uncomplicated influenza-like illness, and who do not have an underlying medical condition that puts them at risk. Hallmarks of progressive illness that warrant antiviral therapy include: shortness of breath, hypoxia, and fast or labored breathing in children, which would suggest oxygen impairment or cardiopulmonary insufficiency; altered mental status, unconsciousness, drowsiness, and seizures, which suggest central nervous system complications; evidence of sustained virus replication or invasive secondary bacterial infection; and severe dehydration, expressed as decreased activity, dizziness, decreased urine output, and lethargy.

The first-line antiviral for treating the H1N1 virus is oseltamivir (Tamiflu); if oseltamivir is not available, it is not possible to administer it to a particular patient, or if the virus is resistant to oseltamivir, the guidelines recommend that clinicians use zanamivir, which is inhaled. To ensure easier access to treatment, public health authorities should distribute antivirals through general practitioners and not primarily through hospitals, to help ensure that individuals get the care they need faster.

"The virus can take a life within a week,” said Nikki Shindo, M.D., a medical officer in WHO's Global Influenza Program. "The week of opportunity is very narrow in regard to the progression of the disease. The medicine needs to be administered before the virus destroys the lungs.”

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