Prevention and Treatment of Novel Influenza A (H1N1) Influenza Virus Infection in Infants and Children

May 13, 2009 3:30 PM ET

This document provides interim guidance for clinicians who are caring for young children with novel influenza A (H1N1) virus infection. As additional information becomes available, the guidance in this document may be updated.

Infants and Children and the Novel H1N1 Virus

Little is currently known about how this novel influenza A (H1N1) virus circulating in people may affect children. However, seasonal influenza and past pandemics, it is known that children, especially those younger than 5 years of age and those who have high risk medical conditions are at increased risk of influenza-related complications. Among children less than 5 years, the risk for severe complications from seasonal influenza is highest among children less than 2 years old.

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

Children with Developmental Disabilities, and Chronic Medical Conditions

Certain children are at higher risk for complications from influenza infection. An investigation of 153 seasonal influenza-associated deaths among children during the 2003-2004 season found that 33% of the children had an underlying condition recognized to increase the risk of influenza-related complications, and 20% had other chronic conditions; 47% had previously been healthy. Chronic neurologic or neuromuscular conditions were present in one third. 

Children at higher risk include infants < 6 months and all children with immune suppression, pregnancy, chronic kidney disease, heart disease, HIV/AIDS, diabetes, asthma or other problems of the lungs, sickle cell disease, and those on long-term aspirin therapy for chronic disorders. In addition, children with any condition that affects respiratory function including neurological conditions such as intellectual and developmental disability, cerebral palsy, spinal cord injuries, seizure disorders, metabolic conditions or other neuromuscular disorders have higher risk.

Other children with an increased risk for complications are those with poor nutritional and fluid intake because of prolonged vomiting and diarrhea, and children with an underlying metabolic disorder such as medium-chain acyl-CoA dehydrogenase (MCAD) deficiency who are unable to tolerate prolonged periods of fasting. Because many children with neurological or metabolic conditions may not have the ability to report onset or worsening of symptoms, delay in identification of influenza infection can lead to additional complications.  In addition, in one study among HIV-infected children who were not taking antiretroviral medication, influenza was more severe and hospitalization and bacterial complications were more common than among uninfected (i.e, non-HIV infected) children.