CDC Updates Recommendations for Antiviral Use

The CDC is urging physicians to use antiviral medications appropriately to treat influenza during the 2009-10 flu season in order to avoid shortages and development of antiviral resistance. "It is very important that people know most children, adolescents and adults with influenza-like illness don't need the medicine," said Anne Schuchat, M.D., director of the CDC’s National Center for Immunization and Respiratory Diseases, during a Sept. 8 media briefing.

"It is people with risk conditions where the illness may get worse or people with severe presentations -- like those hospitalized or who have signs of lower respiratory infection or other severe warning signs -- who need antivirals," said Schuchat during the briefing, which coincided with the agency's release of updated antiviral guidance.

Reports of widespread influenza activity increased in early September, particularly in southeastern states, which started school earlier than the rest of the country, according to Schuchat. There also were reports of localized shortages of antiviral medications.

Schuchat said supplies of the recommended antiviral medications -- oseltamivir (Tamiflu) and zanamivir (Relenza) -- should be adequate, and the CDC is working with state and local public health officials and the commercial sector to address any shortages.

The CDC's updated guidance did not change recommendations issued in May for who should receive the medications. The agency recommends treatment for patients with confirmed or suspected novel influenza A (H1N1) infection who require hospitalization, as well as for the following groups at high risk for flu-related complications:

The CDC also said any patient suspected of having influenza who presents with warning symptoms or signs of lower respiratory tract illness should promptly receive antiviral treatment. Physicians should not wait for laboratory confirmation of illness because antivirals are more effective within 48 hours of onset of illness, and a negative rapid test does not rule out influenza.

New features of the updated guidance include the suggestion that physicians provide patients in high-risk groups with prescriptions that could be filled at the onset of flu symptoms after telephone consultation with the physician.

"We do feel that prompt treatment is important and that the doctor's office may get relatively busy, and it may be reasonable in some circumstances for a phone conversation to be sufficient for a prescription to be filled," Schuchat said.

The guidelines also suggest that physicians can reduce delays in the initiation of treatment by educating patients in high-risk groups about flu symptoms -- including fever, cough, sore throat, body aches, chills, fatigue, vomiting, diarrhea, and runny or stuffy nose -- and the importance of early treatment.

The guidelines also stress that physicians should remind patients receiving antivirals that viral shedding can continue for a few days after the initiation of treatment, and antiviral resistance could become an issue. Thus, patients should continue to follow good hand hygiene and cover their coughs and sneezes to prevent the spread of infection.

Antiviral medications should not be used for postexposure chemoprophylaxis in healthy children or adults, the CDC said. However, postexposure antiviral chemoprophylaxis with either oseltamivir or zanamivir still can be considered for

Schuchat said physicians also can consider "watchful waiting" to see if an exposed person in these high-risk groups develops a fever or respiratory symptoms.

Finally, a study published online Aug. 4 and scheduled to appear in the Oct. 6 issue of Annals of Internal Medicine found that extended-duration zanamivir and oseltamivir chemoprophylaxis appears to be highly efficacious for preventing influenza among immunocompetent white and Japanese adults.

The study, which reviewed seven trials involving more than 7,000 participants, included three trials involving oseltamivir use in unvaccinated subjects; one trial involving zanamivir use in subjects vaccinated with trivalent inactivated influenza vaccine, or TIV; and three trials that included both unvaccinated subjects and subjects vaccinated with TIV.

None of the studies included subjects vaccinated with live, attenuated influenza vaccine, or LAIV, because antiviral medications are contraindicated for two weeks after receipt of LAIV. Furthermore, LAIV should not be administered until 48 hours after cessation of antiviral therapy.