Influenza (Flu)

Alerts, Advisories and Updates

CDC Announces Change in Recommendations for use of Antivirals; Clinicians Should Not Prescribe Two Common Antivirals

The Centers for Disease Control and Prevention (CDC) announced today that clinicians should not prescribe two common antivirals (amantadine and rimantadine) to treat or prevent influenza during the current influenza season (2005-2006). Laboratory testing by CDC on the predominant strain of influenza (H3N2) currently circulating in the United States shows that it is resistant to these drugs.

CDC has tested a representative sample of 120 influenza A (H3N2) virus isolates from across the country and found that 109 (or 91 percent) were resistant to amantadine and rimantadine. This represents a sharp increase from last year when only 11 percent of isolates tested were resistant and 1.9 percent were resistant the year before that. The CDC has not yet identified the reason for the sharp increase in resistance.

All H3 and H1 influenza viruses tested to date are susceptible to the other commonly used antivirals (oseltamivir and zanamivir). CDC is recommending that anyone currently on amantadine or rimantidine for either treatment or prevention purposes should be switched to either oseltamivir or zanamivir.

Clinicians should continue to use the rapid influenza test or constellation of typical influenza symptoms to determine which patients should be treated with oseltamivir or zanamivir. In general, influenza presents with sypmptoms worse than the common cold, and include fever, body aches, extreme tiredness, and dry cough which are more common and intense than common colds. Influnza usually does not present with runny or stuffy noses which is more common among people with colds.

The use of either oseltamivir or zanamivir to treat influenza must begin within 24-48 hours of devoloping symptoms. When used in this manner, these drugs are not a cure but can reduce influenza symptoms and may shorten the time one is sick by 1 or 2 days. The drugs also may make one less contagious. For treatment, oseltamivir and zanamivir must be taken for 5 consecutive days. For prevention, these medications are taken while at risk and are about 70% to 90% effective in preventing illness. For prescribing information go to www.cdc.gov/flu/professionals/antiviralback.htm

While the southwest and western states are seeing widespread influenza activity, Rhode Island continues to only see sporadic cases of influenza. For up to date information please visit either HEALTH's website www.health.ri.gov or CDC's influenza website www.cdc.gov/flu/weekly/fluactivity.htm