Study highlights variable use and rising costs of antivirals in treating pediatric influenza in the U.S.

By Dr. Chinta SidharthanNov 16 2023Reviewed by Susha Cheriyedath, M.Sc.

In a recent study published in the journal Pediatrics, a team of researchers in the United States (U.S.) conducted a cross-sectional study to understand the trends in antiviral usage among adolescents and children suffering from influenza in the U.S. based on dispensing rates and costs.

Study: Trends in Outpatient Influenza Antiviral Use Among Children and Adolescents in the United States. Image Credit: Dragana Gordic / Shutterstock

Background

Influenza is highly prevalent among the pediatric population in the U.S., with approximately 10% of children developing symptomatic influenza and close to 30% of children each year having asymptomatic influenza infections. Young children with comorbidities are at an increased risk of complications arising from influenza infections, such as lower respiratory tract bacterial infections, seizures, encephalitis, and bacterial meningitis, which can lead to hospitalization and even death.

To limit the transmission of the infection within the household, reduce the duration of the illness, and prevent the need for hospitalization or the development of complications such as pneumonia and otitis media that can increase antibiotic use and other healthcare costs, influenza infections in children are often treated with antivirals in the outpatient setting. The antiviral oseltamivir has been recommended by the Centers for Disease Control and Prevention (CDC) for treating influenza infections in children within 48 hours of the onset of symptoms. The Food and Drug Administration (FDA) has approved four antivirals for the treatment of influenza — intravenous peramivir, inhaled zanamivir, and oral oseltamivir or baloxavir. Of these, oseltamivir is the only one approved for children of all ages, especially those below five years of age.

About the study

In the present study, the researchers attempted to understand the trends in antiviral usage for the treatment of influenza infections in the pediatric population in the U.S. Studies from 2019 following the hemagglutinin 1 neuraminidase 1 (H1N1) pandemic reported that despite the recommendations for antiviral use, oseltamivir use among those with confirmed influenza infections was only 15%. Furthermore, antiviral use also showed significant variation across influenza seasons and geographic locations within the same season.

The researchers believe that recent patterns of antiviral prescriptions could have been affected by factors such as availability, uncertainties about the effectiveness of antivirals, potential risks of antivirals, and costs. Therefore, an updated analysis of antiviral usage for treating influenza infection among the pediatric population and optimizing antiviral prescriptions is essential. This cross-sectional study analyzed data collected from participants under the age of 18 between July 2010 and July 2019.

The pharmacy dispensing claims in the outpatient setting for zanamivir, baloxavir, and oseltamivir were used to identify antiviral exposures. Since peramivir is administered intravenously, its usage among non-hospitalized individuals would be limited, and therefore, it was excluded from the analysis. Based on the national guidelines, prescribing antivirals for less than or equal to five days was defined as acute infection treatment, while those for more than five days were considered prophylactic.

Data from the CDC's Flu Activity and Surveillance program was used to evaluate seasonal influenza activity. The primary outcomes examined in the study were antiviral dispensing rates deciphered from the total number of pharmacy claims for zanamivir, baloxavir, and oseltamivir divided by the number of children enrolled in the outpatient setting. The rates of antiviral dispensing for treatment and prophylactic use were also calculated based on the prescribed duration of antiviral use.

Results

The results indicated significant variation in the costs and usage of antivirals to treat influenza infections in adolescents and children. The rates for guideline-concordant antiviral treatment of young children who were at high risk of complications associated with influenza infections were also found to be low, and antiviral treatment for influenza infections varied substantially across geographic regions.

The study found that although children under the age of six were more susceptible to symptomatic infections, the use of antivirals for treating influenza infections was higher among children between the ages of six and 17 years. Only 37% and 34% of children under two years of age and between two and five years of age, respectively, were treated for influenza infections using antivirals.

The study also found that in the last 10 years, along with an increase in antiviral utilization, the cost of antivirals for treating influenza infections had also increased, with intermittent periods of shortages of oseltamivir.

Conclusions

Overall, the findings suggested significant variation in the usage of antivirals to treat pediatric cases of influenza, including variations based on age and geographic location. The study also reported a significant increase in antiviral costs over the previous 10 years and low antiviral usage among children less than six years of age. These results highlight the potential areas for improvement in the treatment of pediatric influenza infections.