Interim Guidance for Clinicians on the Prevention and Treatment of Swine-Origin Influenza Virus Infection in Young Children

April 28, 2009 11:00 PM ET

This document provides interim guidance for clinicians who are caring for young children with confirmed or suspected swine-origin influenza A (H1N1) virus infection.

Background

Young children and swine-origin influenza virus (S-OIV)
Little is currently known about how this new S-OIV circulating in people may affect children. However, we know from seasonal influenza and past pandemics that young children, especially those younger than 5 years of age and children who have high risk medical conditions, are at increased risk of influenza-related complications.

Illnesses caused by influenza virus infection are difficult to distinguish from illnesses caused by other respiratory pathogens based on symptoms alone.  Young children are less likely to have typical influenza symptoms (e.g., fever and cough) and infants may present to medical care with fever and lethargy, and may not have cough or other respiratory symptoms or signs.

Influenza-associated deaths among children, while uncommon, do occur with seasonal influenza with an estimated average of approximately 92 influenza-related pediatric deaths each year in the United States.  Some deaths in children have been associated with co-infection with influenza and Staphylococcus aureus, particularly methicillin resistant S. aureus (MRSA).

Symptoms of severe disease may include:

• Apnea
• Tachypnea
• Dyspnea
• Cyanosis
• Dehydration
• Altered mental status
• Extreme irritability

Treatment and prevention of swine flu

No vaccine is currently available to prevent S-OIV infection and it is thought unlikely that seasonal influenza vaccine will provide protection against this new virus.  While not a substitute for a vaccine, a number of other interventions may be used to decrease the risk of infection and possible complications from S-OIV infection in children.

Influenza antiviral medications for use in children age 1 year and older

Antiviral treatment with oseltamivir or zanamivir is recommended for children with confirmed or probable S-OIV infection. See case definitions.  Empiric antiviral treatment is also recommended for children with suspected cases of swine influenza A (H1N1) virus infection, especially those with severe illness. Antiviral treatment with zanamivir or oseltamivir should be initiated as soon as possible after the onset of symptoms. Evidence for benefits from treatment in studies of seasonal influenza is strongest when treatment is started within 48 hours of illness onset. However, some studies of treatment of seasonal influenza have indicated benefit, including reductions in mortality or duration of hospitalization even for patients whose treatment was started more than 48 hours after illness onset.  Recommended duration of treatment is five days. Recommendations for use of antivirals may change as data on antiviral effectiveness, side effects and antiviral susceptibilities become available.  Antiviral doses recommended for treatment of S-OIV infection in children 1 year of age or older are the same as those recommended for seasonal influenza (Table 1).

Table 1. Swine-origin influenza antiviral medication dosing recommendations.
(Table extracted from IDSA guidelines for seasonal influenza.)

Agent, group		Treatment	Chemoprophylaxis
Oseltamivir
Adults		75-mg capsule twice per day for 5 days	75-mg capsule once per day
Children (age, 12 months or older), weight:	15 kg or less	60 mg per day divided into 2 doses	30 mg once per day
	15�23 kg	90 mg per day divided into 2 doses	45 mg once per day
	24�40 kg	120 mg per day divided into 2 doses	60 mg once per day
	>40 kg	150 mg per day divided into 2 doses	75 mg once per day
Zanamivir
Adults		Two 5-mg inhalations (10 mg total) twice per day	Two 5-mg inhalations (10 mg total) once per day
Children		Two 5-mg inhalations (10 mg total) twice per day (age, 7 years or older)	Two 5-mg inhalations (10 mg total) once per day (age, 5 years or older)

Children Younger than 1 Year of Age

Children less than one year of age are at higher risk for complications associated with seasonal human influenza virus infections compared to older children, and the risk of influenza complications is especially high for children less than 6 months of age. The characteristics of human infections with S-OIV are still being studied, and it is not known whether infants are at higher risk for complications associated with S-OIV infection compared to older children.  However, children less than 1 year old are known to be at increased risk of complications from seasonal influenza infection and during previous pandemics.  Limited safety data on the use of oseltamivir (or zanamivir) is available from children less than one year of age, and oseltamivir is not licensed for use in children less than 1 year old.  Available data comes from use of oseltamivir for treatment of seasonal influenza. However, these data suggest that severe adverse events are rare, and the Infectious Diseases Society of America recently noted that “… limited retrospective data on the safety and efficacy of oseltamivir in this young age group have not demonstrated age-specific drug-attributable toxicities to date.”.

Because infants typically have higher rates of morbidity and mortality from influenza compared to healthy older children, infants with S-OIV infections may benefit from treatment using oseltamivir.  Oseltamivir use for children less than 1 year old was recently approved by the FDA under an Emergency Use Authorization (EUA), and dosing for these children is age-based. (Table 2).

Table 2. Dosing recommendations for antiviral treatment of children younger than 1 year using oseltamivir.

Age	Recommended treatment dose for 5 days
<3 months	12 mg twice daily
3-5 months	20 mg twice daily
6-11 months	25 mg twice daily

Use of fever-reducing medications in children

Aspirin or aspirin-containing products (e.g. bismuth subsalicylate – Pepto Bismol) should not be administered to any confirmed or suspected ill case of swine influenza A (H1N1) virus infection aged 18 years old and younger due to the risk of Reye syndrome. For relief of fever, other anti-pyretic medications are recommended such as acetaminophen or non steroidal anti-inflammatory drugs.

Antiviral Chemoprophylaxis

For antiviral chemoprophylaxis of S-OIV infection, either oseltamivir or zanamivir are recommended for children 1 year of age or older (Table 1). Oseltamivir can be used for chemoprophylaxis under the EUA for children less than 1 year-old (Table 3). Under this EUA, chemoprophylaxis is not recommended for infants less than 3 months old unless the situation is judged to be critical. Duration of antiviral chemoprophylaxis post-exposure is 10 days after the last known exposure to an ill confirmed case of swine influenza A (H1N1) virus infection. For pre-exposure protection, chemoprophylaxis should be given during the potential exposure period and continued for 10 days after the last known exposure to an ill confirmed case of swine influenza A (H1N1) virus infection.

Table 3.�Dosing recommendations for antiviral chemoprophylaxis of children younger than 1 year using oseltamivir.

Age	Recommended prophylaxis dose for 10 days
<3 months	Not recommended unless situation judged critical due to limited data on use in this age group
3-5 months	20 mg once daily
6-11 months	25 mg once daily

Antiviral chemoprophylaxis with either oseltamivir or zanamivir is recommended for the following children:

1. Household close contacts who are at high-risk for complications of influenza (children younger than 5 years old , pregnant women, persons ≥65 years-old and those with certain chronic medical conditions) of a confirmed or suspected case.
2. School children or daycare attendees who are at high-risk for complications of influenza (children younger than 5 years old, pregnant women, persons ≥65 years-old and those with certain chronic medical conditions) who had close contact (face-to-face) with a confirmed, probable, or suspected case.
3. Children who traveled to Mexico who are at high-risk for complications of influenza (children younger than 5 years old pregnant women, persons ≥65 years-old and those with certain chronic medical conditions).

Other measures to prevent swine influenza in children

• In addition to antiviral medications, other information on measures that can help prevent the spread of influenza can be found at the CDC H1N1 Flu Website under the following headings:
• Interim Recommendations for Facemask and Respirator Use in Certain Community Settings Where Swine Influenza A (H1N1) Virus Transmission Has Been Detected
• Interim Guidance for Swine influenza A (H1N1): Taking Care of a Sick Person in Your Home
• Interim Guidance on Antiviral Recommendations for Patients with Confirmed or Suspected Swine Influenza A (H1N1) Virus Infection and Close Contacts
• Interim Guidance for Infection Control for Care of Patients with Confirmed or Suspected Swine Influenza A (H1N1) Virus Infection in a Healthcare Setting Apr 24, 2009

Interim CDC Guidance for Nonpharmaceutical Community Mitigation in Response to Human Infections with Swine Influenza (H1N1) Virus Apr 26, 2009, 11:45 PM ET