Treatment of H1N1 Influenza A (Swine Flu) in High-Risk Populations: Guidance for Clinicians

Deborah Brauser

Disclosures

May 04, 2009

In This Article

Who Is at Higher Risk With H1N1 Flu?

Although data at this point are insufficient to determine who is at higher risk for complications of swine-origin influenza (S-OIV) A (H1N1), "It's reasonable to assume that the same age and risk groups who are at higher risk for seasonal influenza complications should be also considered at higher risk for swine influenza complications," reports the Centers for Disease Control and Prevention (CDC) on their Website. The CDC has issued several suggested guidelines for clinicians who treat these high-risk groups, including children, pregnant women, new mothers, and HIV-infected adults and adolescents.

High-Risk Group #1: Children

On their Website, the CDC reports that little is currently known about how this new S-OIV may affect children. "However, we know from seasonal influenza and past pandemics that young children, especially those younger than 5 years of age and those with high-risk medical conditions, are at increased risk of influenza-related complications." They currently estimate an average of approximately 92 influenza-related pediatric deaths each year in the United States.

During a conference call on May 1, CDC influenza expert Tim Uyeki, MD, MPH, MPP, said that the great majority of cases reported in the United States have been in those under 18 years of age. "So children have been heavily affected. And I would expect attack rates to continue to be high among pediatric populations."

Although seasonal influenza vaccine is unlikely to provide protection against this new virus, a number of other interventions may decrease the risk for infection and possible complications.

What Is the Recommended Treatment for Children 1 Year of Age and Older?

  • For those with a confirmed or probable S-OIV infection, antiviral treatment with oseltamivir or zanamivir is recommended and should be initiated as soon as possible after the onset of symptoms. (For case definitions, go to www.cdc.gov/h1n1flu/casedef_swineflu.htm)

  • The recommended duration of treatment is 5 days, but that may change as data on antiviral effectiveness, side effects, and antiviral susceptibilities become available. Recommended antiviral doses for treatment of S-OIV infection are the same as those recommended for seasonal influenza and can be found at http://www.cdc.gov/h1n1flu/childrentreatment.htm

  • For children older than 1 year with suspected cases of swine influenza A (H1N1) virus infection, especially those with severe illness, empiric antiviral treatment is also recommended.

How Should Children Younger Than 1 Year Be Treated?

Currently, there are only limited safety data available on the use of oseltamivir or zanamivir for seasonal influenza in this age group, and oseltamivir is not licensed for use in children younger than 1 year.

Because infants typically have high rates of morbidity and mortality from influenza, however, the CDC reports that infants with S-OIV infections may benefit from treatment with oseltamivir. In fact, under an Emergency Use Authorization (EUA), oseltamivir was recently approved by the US Food and Drug Administration for use in children younger than 1 year.

The dosing recommendations for treating S-OIV influenza in infants are now:

  • < 3 months old = oseltamivir 12 mg twice daily

  • 3-5 months old = oseltamivir 20 mg twice daily

  • 6-11 months old = oseltamivir 25 mg twice daily

When considering fever-reducing medications, the CDC recommends the following:

  • Do not administer aspirin or aspirin-containing products for confirmed or suspected case of influenza A (H1N1) virus infection in any child 18 years of age or younger due to the risk for life-threatening Reye's syndrome.

  • Instead, antipyretic medications such as acetaminophen or nonsteroidal anti-inflammatory drugs are recommended for the relief of fever.

What Are the Current Antiviral Chemoprophylaxis Guidelines for This Group?

Antiviral chemoprophylaxis is currently recommended for:

  • Children with household contacts with confirmed, probable, or suspected cases of H1N1 infection;

  • School children or daycare attendees who are at high risk for complications of influenza and who have had face-to-face contact with a confirmed, probable, or suspected case of H1N1 influenza;

  • Children who traveled to Mexico recently and are at high risk for complications of influenza; and

  • Children with chronic medical conditions.

The CDC's current chemoprophylaxis treatment recommendations are:

  • For children 1 year of age or older, treatment with either oseltamivir or zanamivir is recommended for antiviral chemoprophylaxis of S-OIV infection.

  • For those 3-11 months of age, oseltamivir can be used under an EUA (at doses of 20 mg once daily for those 3-5 months of age and 25 mg once daily for those 6-11 months of age).

  • For infants younger than 3 months, chemoprophylaxis is not recommended unless the situation is judged to be critical.

Chemoprophylaxis should be given during a potential exposure period and should be continued for 10 days after the last known exposure to a confirmed case of H1N1 infection.

Children With Special Conditions

In regard to seasonal influenza, certain children are more at risk for complications. In fact, a recent study found that almost half of the children who died from influenced-related causes had an underlying medical condition. These conditions include immunosuppression, chronic kidney disease, heart disease, HIV and AIDS, diabetes, asthma or problems with the lungs, sickle cell disease, and chronic neurologic conditions, cerebral palsy, and seizure disorders.

Another high-risk group of children includes those with poor nutritional or fluid intakes because of prolonged vomiting and diarrhea, as well as children with an underlying metabolic disorder.

These children should be particularly monitored for symptoms of influenza. Additional guidance for children with special healthcare needs is expected to be posted on the CDC site soon.

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