CDC issues antiviral priorities for flu season

Supplies at local level may effect choices

The Centers for Disease Control and Prevention (CDC) has issued interim guidelines for use of antiviral medications during the 2004-2005 influenza season. The guidelines are summarized as follows:

1. The CDC encourages the use of amantadine or rimantadine for chemoprophylaxis and use of oseltamivir or zanamivir for treatment as supplies allow, in part, to minimize the development of adamantane resistance among circulating influenza viruses.

2. People who are at high risk of serious complications from influenza may benefit most from antiviral medications. Therefore, in general, people who fall into these high-risk groups should be given priority for use of influenza antiviral medications:

Treatment

Any person experiencing a potentially life-threatening influenza-related illness should be treated with antiviral medications.

Any person at high risk for serious complications of influenza and who is within the first two days of illness onset should be treated with antiviral medications. (Pregnant women should consult their primary provider regarding use of influenza antiviral medications.)

Antiviral Use in Children: Rimantadine is approved for prophylaxis of influenza among children older than 1 year and for treatment and prophylaxis of influenza among adults. Although rimantadine is approved only for prophylaxis of influenza among children, certain specialists in the management of influenza consider it appropriate for treatment of influenza among children. Also available for treatment of children are amantadine (children older than 1 year), oseltamivir (children older than 1 year), or zanamivir (children older than 7 years).

Chemoprophylaxis

All people who live or work in institutions caring for people at high risk of serious complications of influenza infection should be given antiviral medications in the event of an institutional outbreak. This includes nursing homes, hospitals, and other facilities caring for persons with immunosuppressive conditions, such as HIV/AIDS. When vaccine is available, vaccinated staff require chemoprophylaxis only for the two-week period following vaccination. Vaccinated and unvaccinated residents should receive chemoprophylaxis for the duration of institutional outbreak activity. Rapid tests or other influenza tests should be used to confirm influenza as the cause of outbreaks as soon as possible. However, treatment and chemoprophylaxis should be initiated if influenza is strongly suspected and test results are not yet available. Other outbreak control efforts such as cohorting of infected people and the practice of respiratory hygiene and other measures also should be implemented.

All people at high risk of serious influenza complications should be given antiviral medications if they are likely to be exposed to others infected with influenza. For example, when a high-risk person is part of a family or household in which someone else has been diagnosed with influenza, the exposed high-risk person should be given chemoprophylaxis for seven days.

3. Antiviral medications can be considered in other situations when the available supply of such medications is locally adequate.

Chemoprophylaxis of people in communities where influenza viruses are circulating, which typically lasts for six to eight weeks:

  • People at high risk of serious complications who are not able to get vaccinated.
  • People at high risk of serious complications who have been vaccinated but have not had time to mount an immune response to the vaccine. In adults, chemoprophylaxis should occur for a period of two weeks after vaccination. In children younger than 9 years, chemoprophylaxis should occur for six weeks after the first dose or two weeks after the second dose depending on whether the child is scheduled to receive one or two doses of vaccine.
  • People with immunosuppressive conditions who are not expected to mount an adequate antibody response to influenza vaccine.
  • Health care workers with direct patient care responsibilities who are not able to obtain vaccine.

    Treatment of infected adults and children older than 1 year who do not have conditions placing them at high risk for serious complications secondary to influenza infection.

4. Where the supplies of both influenza vaccine and influenza antiviral medications may not be sufficient to meet demand, the CDC does not recommend the use of influenza antiviral medications for chemoprophylaxis of nonhigh-risk people in the community.

(Editor’s note: The CDC antiviral interim guidelines and other influenza directives may be updated as the flu season unfolds at www.cdc.gov/flu.)