Combating Influenza With Antiviral Therapy in the Pediatric Population

Kara A. Townsend, Pharm.D.; Lea S. Eiland, Pharm.D.

Disclosures

Pharmacotherapy. 2006;26(1):95-103. 

In This Article

Abstract and Introduction

Influenza viruses are accountable for annual epidemics worldwide that result in significant morbidity and mortality. In preschool and school-aged children, prospective surveillance of influenza demonstrates yearly infection rates of 15-42%. Children can easily transmit the virus to other children, to employees in day-care and school settings, and to family members. Two classes of antiviral drugs, the adamantine derivatives (amantadine, rimantadine) and neuraminidase inhibitors (zanamivir and oseltamivir), have been approved for treatment and prophylaxis of influenza in the pediatric population. Duration of clinical symptoms decreases and daily activities are resumed sooner when therapy is begun within 48 hours of the onset of influenza symptoms. Mechanism of action, adverse effects, and development of resistant variants differ between the two drug classes. To our knowledge, head-to-head clinical trials between the classes and involving the neuraminidase inhibitors are nonexistent. Antiviral agents do not replace the annual influenza vaccine, and clinical trials indicate that amantadine, rimantadine, zanamivir, and oseltamivir are safe and effective for administration in the pediatric population.

Prospective surveillance of influenza demonstrates annual attack rates of 15-42% in preschool and school-aged children.[1] Depending on the influenza season, which is usually November-March, the rate of annual outpatient visits attributable to influenza varies from 6-29/100 children. Also, an estimated 3-5% of children experience influenza-associated acute otitis media annually. Influenza and its complications lead to a 10-30% increase in the number of antimicrobial treatment courses prescribed for children during influenza season. Also, antecedent influenza infection is associated with development of severe pneumococcal pneumonia in children. Healthy children younger than 24 months are now known to have as great a risk for influenza-associated hospitalization as previously recognized high-risk groups. Young children are hospitalized for influenza at rates similar to those of the elderly, for whom routine immunization has been recommended since 2000. The fatality rate in children has been estimated at 3.8/100,000.

Influenza can be treated and possibly prevented with antiviral drug therapy. Antiviral drugs are administered as an adjunct to the vaccine and should not be considered a substitute for vaccination. Amantadine, rimantadine, zanamivir, and oseltamivir are the four licensed antiviral agents available in the United States. These drugs halt or impede the ability of the influenza virus to infect respiratory epithelial cells. When administered within 2 days of the start of the illness in otherwise healthy adults and children, amantadine and rimantadine can reduce the duration of uncomplicated influenza A infection. Zanamivir and oseltamivir can reduce the duration of uncomplicated influenza A and B illness by approximately 1 day compared with placebo. None of these antiviral agents has been effective in preventing serious influenza-related complications, such as bacterial or viral pneumonia, in otherwise healthy adults or children.[2] However, the neuraminidase inhibitors have been associated with decreased antibiotic treatment for complications.

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