Influenza Antiviral Treatment Underutilized Among Eligible Children, Adolescents

Data from 2 national surveillance networks indicate that influenza antiviral treatment is underutilized among eligible children and adolescents, according to a study published in the CDC’s Morbidity and Mortality Weekly Report.¹

Each year, seasonal influenza infections result in tens of thousands of hospitalizations among American children and adolescents. However, influenza vaccinations and early antiviral treatment initiation can reduce the risk of complications.

Antiviral treatment is recommended as soon as possible for patients with suspected or confirmed influenza who are hospitalized; have severe, complicated, or progressive illness; or are at high risk of complications. Treatment should not be delayed for laboratory confirmation in high-risk individuals, including those with certain underlying medical conditions and children younger than 5 years; those younger than 2 years are at the highest risk.

During the 2022 to 2023 season, antiviral treatment was underutilized among hospitalized children and adolescents with laboratory-confirmed influenza compared with pre–COVID-19 pandemic seasons. To build on these findings, the researchers analyzed treatment patterns during the 2023 to 2024 influenza season, focusing on children and adolescents with laboratory-confirmed influenza, specifically those hospitalized and those at higher risk for complications in the outpatient setting.

Influenza antiviral treatment remains underutilized among eligible children and adolescents, particularly in outpatient settings. | Image Credit: cristianstorto - stock.adobe.com

They collected data from 2 US influenza surveillance networks: the Influenza Hospitalization Surveillance Network (FluSurv-NET) and the New Vaccine Surveillance Network (NVSN). The researchers then analyzed eligible patients from both networks with recorded data between October 1, 2023, to April 30, 2024.

Eligible FluSurv-NET patients were those residing in the surveillance catchment area and hospitalized with laboratory-confirmed influenza.² Data were collected through medical records reviews using a standardized case report form, focusing on a random sample of cases stratified by age, site, and month of admission from 12 sites. All sampled patients younger than 18 years were included in the study.

Conversely, eligible NVSN patients were younger than 18 years, lived in the catchment area, and were diagnosed with acute respiratory illness and laboratory-confirmed influenza.³ Data were collected through medical chart reviews and parent or guardian interviews. All hospitalized patients were included, but those in the outpatient setting were included only if they met the CDC guidelines for influenza antiviral treatment.

The researchers defined influenza antiviral treatment as the documented prescription or receipt of baloxavir, peramivir, oseltamivir, or zanamivir.¹ They calculated treatment rates by dividing the number of patients treated with or prescribed antivirals by the total number recommended for antiviral treatment. For historical context, they also assessed antiviral treatment trends from the 2017 to 2018 season through the 2023 to 2024 season.

The overall percentage of hospitalized patients younger than 18 years with laboratory-confirmed influenza who received antiviral medications during the 2017 to 2018 season was 86% in FluSurv-NET and 70% in NVSN. However, the researchers observed a decline in antiviral treatment rates starting with the 2019 to 2020 season compared with prepandemic levels. To further understand these trends, they analyzed 573 eligible outpatient visits and 283 hospitalizations in NVSN, along with 1846 hospitalizations in FluSurv-NET during the 2023 to 2024 influenza season.

Among those hospitalized within the NVSN and FluSurv-NET, the largest percentage of patients were aged 5 to 11 years (42% and 39%, respectively) and were non-Hispanic White patients (36% and 33%, respectively). Conversely, most patients in the outpatient setting were aged 2 to 4 years (42%) and were non-Hispanic Black patients (43%).

Also, the researchers found that 31% of those in the outpatient setting who were recommended antiviral treatments were prescribed them, all of whom were prescribed oseltamivir. Prescriptions were most prevalent among those younger than 6 months (49%) and lowest among those aged 2 to 4 years (21%).

As for hospitalized patients in NVSN and FluSurv-NET, 52% and 59% received antiviral treatment, respectively. Among patients within NVSN, antiviral treatment prevalence was highest among those younger than 6 months (68%) and lowest among those aged 2 to 4 years (43%). As for those within FluSurv-NET, treatment prevalence was highest among those younger than 6 months (73%) but lowest in those aged 12 to 17 years (49%). Overall, most treated patients received oseltamivir (99%).

In both settings, the percentage of patients who received antiviral treatment for laboratory-confirmed influenza increased with the number of underlying medical conditions. For outpatient care, it rose from 28% among those with no underlying conditions to 57% among those with 3 or more. As for hospitalized patients, it increased from 45% to 75% and from 55% to 77% among those in NVSN and FluSurv-NET, respectively.

Overall, during the 2023 to 2024 season, about half (41%-48%) of children and adolescents with an influenza-associated hospitalization and about two-thirds (69%) of those with a related outpatient visit did not receive recommended antiviral treatment. The researchers noted that this demonstrates missed opportunities to reduce influenza complication risks, emphasizing the importance of increasing awareness about current antiviral treatment recommendations.

Lastly, they acknowledged potential limitations to their findings, including FluSurv-NET and NVSN catchment areas do not include the entire US population. Therefore, their findings may not be generalizable nationwide. Despite this, the researchers reiterated the CDC’s recommendations for influenza antiviral treatment due to their concerning findings.

“The decrease in influenza antiviral use among children and adolescents with laboratory-confirmed influenza since the COVID-19 pandemic is concerning,” the authors concluded. “Health care providers are reminded that children and adolescents with suspected or confirmed influenza who are hospitalized or have higher risk for influenza complications should receive prompt antiviral treatment.”

References

1. Frutos AM, Ahmad HM, Ujamaa D, et al. Underutilization of influenza antiviral treatment among children and adolescents at higher risk for influenza-associated complications — United States, 2023–2024. MMWR Morbidity and Mortality Weekly Report. 2024;73(45):1022-1029. doi:10.15585/mmwr.mm7345a2

2. Influenza Hospitalization Surveillance Network (FluSurv-NET). CDC. October 23, 2023. Accessed November 19, 2024. https://www.cdc.gov/fluview/overview/influenza-hospitalization-surveillance.html

3. New Vaccine Surveillance Network (NVSN). CDC. May 6, 2024. Accessed November 19, 2024. https://www.cdc.gov/nvsn/php/about/index.html