WHO: In Treating H1N1, Save Antivirals for High-risk Cases

Lisa Schnirring Staff Writer
Aug 21, 2009 (CIDRAP News) – The World Health Organization (WHO) yesterday released new guidelines for using antivirals to treat patients with novel H1N1 influenza infections, signaling a shift toward reserving the medications for people with severe infections and those at high risk for complications.

The new recommendations for managing pandemic H1N1 infections with antivirals are included in a 91-page document on pharmacologic management of all influenza types. An earlier document on clinical management of novel flu patients, issued in May about a month into the novel flu outbreak, briefly reviewed the role of antivirals, but did not give detailed information about their use in different patient populations.

The WHO, in a briefing note today on the new guidance, said the new guidelines were developed by an international expert panel that reviewed all available safety and efficacy studies. They focused on the neuraminidase inhibitors, oseltamivir and zanamivir, because the pandemic H1N1 virus is susceptible to both drugs (and is resistant to the older adamantane drugs). The panel concluded that both drugs can significantly reduce the risk of pneumonia and the need for hospitalization.

Healthy patients with uncomplicated infections should not be treated with antivirals, the group wrote. Some countries, such as the United Kingdom, have been prescribing oseltamivir for any patient with a suspected or confirmed novel flu infection.

For patients who have severe illness or are in a deteriorating condition, the WHO recommends oseltamivir treatment as soon as possible, preferably within 48 hours, though the drug should still be given even if started later.

Pregnant women and those with underlying medical conditions such as asthma, obesity, or diabetes should be treated with oseltamivir or zanamivir as soon as possible after the onset of flulike symptoms, the WHO experts advise.

Because about 40% of severe case are occurring in otherwise healthy children and adults, the WHO urges healthcare providers to be alert for sudden deterioration in clinical condition, which would warrant higher doses and longer duration of oseltamivir treatment than normally prescribed. Danger signs include symptoms such as shortness of breath, difficulty breathing, changes in mental status, and a high fever that persists.

The WHO noted that two recent reports in medical journals raised questions about the usefulness and side effects of antivirals in children. The expert panel considered those reports in making its recommendation that children who have severe or deteriorating illness, plus those who have underlying medical conditions, receive antiviral treatment, the agency said. However, the group said healthy children older than 5 years should not be given antivirals unless their illness persists or worsens.