Antivirals for Influenza Underutilized Among Vulnerable Children, Adolescents

Antiviral treatment of children and adolescents hospitalized for influenza declined significantly from 70%– 86% during the 2017–18 respiratory virus season to less than 60% (52%-59%) in 2023–24, according to findings published in CDC’s Morbidity and Mortality Weekly Report.¹

The analysis of data from 2 national surveillance networks also revealed undertreatment in outpatient settings, where only 31% of children and youth at higher risk for complications of the virus were prescribed the recommended medications.¹

©vinnstock/Shutterstock.com

The CDC recommends that antiviral treatment be initiated 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.¹ Prompt administration of antivirals can reduce odds of intensive care unit admission and mortality among hospitalized children and adolescents, they added. Hospitalization rates for influenza are highest among infants younger than 1 year; the highest risk for influenza-related complications is among those younger than 2 years of age.2

Data from a CDC analysis published in late 2023³ demonstrated that antiviral treatment was underutilized during the 2022-2023 respiratory virus season among hospitalized children and adolescents with laboratory-confirmed influenza compared with pre–COVID-19 pandemic seasons. The current study analyzes antiviral treatment patterns during the 2023 to 2024 influenza season for comparison. For historical context, the research team also assessed antiviral treatment trends from the 2017 to 2018 season through the 2023 to 2024 season.¹

Study data were collected from the Influenza Hospitalization Surveillance Network (FluSurv-NET)⁴ and the New Vaccine Surveillance Network (NVSN),⁵ analyzing individuals from both networks with recorded data between October 1, 2023, to April 30, 2024.

FluSurv-NET collects data from people of all ages and for the study authors defined a case as a hospitalization with laboratory-confirmed influenza for anyone residing in the surveillance catchment area. A random sample of cases included patients aged younger than 18 years and was stratified by age, site, and month of admission from 12 sites.¹

NVSN collects data specifically on individuals younger than age 18 with acute respiratory illness (ARI) in both outpatient and hospital settings at 7 sites. Cases were defined as ARI and laboratory-confirmed influenza in anyone living in the catchment area and included all hospitalized patients but only those from outpatient settings who met the CDC guidelines for influenza antiviral treatment.¹

FINDINGS

During the 2017-2018 season, the overall percentage of individuals younger than 18 years hospitalized with a confirmed diagnosis of influenza who received antiviral therapy was 86% in FluSurv-NET and 70% in NVSN. The decline in treatment of interest began with the 2019 to 2020 season, according to the study, and has remained lower since.¹

Hospitalized patients. When investigators analyzed patient characteristics across NVSN and FluSurv-NET for the 2022-2023 flu season, they found the largest percentage of hospitalized patients were aged 5 to 11 years (42% and 39%, respectively) and non-Hispanic and White patients (36% and 33%, respectively)

Among hospitalized patients in NVSN, 52% received antiviral treatment and among those in the FluSurv-NET cohort, 59% received the therapy. Across both surveillance populations, prevalence of antiviral treatment was highest among those younger than 6 months (68%, NVSN; 73% FluSurv-NET). In NVSN antiviral treatment was lowest among children aged 2 to 4 years (43%) and in FluSURV-Net, among those aged 12 to 17 years (49%). Overall, 99% of patients treated while hospitalized received oseltamivir with more than half of each population (68% NVSN; 60% FluSURV-Net) receiving the therapy on the day of admission. An average of 31.5% of hospitalized patients across the 2 surveillance networks did not receive treatment until 1 or more days after admission.

NSVN Outpatient Settings. In NSVN outpatient settings, the largest percentage of patients with influenza were much younger (aged 2 to 4 years; 42%) than those hospitalized and were non-Hispanic Black or African American patients (43%), according to the results.

In the outpatient settings during 2022-2023, researchers reported, 31% of children and adolescents who were recommended to be treated with antivirals were prescribed them and all prescriptions were for oseltamivir. Infants younger than age 6 months received the highest proportion of antiviral prescriptions (49%) while children aged 2 to 4 years received the lowest (21%).

Underlying conditions. The percentage of patients in both settings who received antiviral treatment for influenza increased along with the number of underlying 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, treatment 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 opportunities missed to reduce complications from influenza among this vulnerable young population require a focus on increasing awareness about current antiviral treatment recommendations, said authors.

Among the limitations to their findings the authors note that FluSurv-NET and NVSN catchment areas do not include the entire US population, limiting the generalization of the results across the country. They also could not account for potential outpatient antiviral treatment prior to hospitalization.

“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.

2. CDC. Influenza antiviral medications: summary for clinicians. Atlanta, GA: US Department of Health and Human Services, CDC; 2024 Accessed September 27, 2024. https://www.cdc.gov/flu/hcp/antivirals/summary-clinicians.html?CDC_AAref_Val=https://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm.

3. White EB, O’Halloran A, Sundaresan D, et al. High influenza incidence and disease severity among children and adolescents aged <18 years—United States, 2022–23 season. MMWR Morb Mortal Wkly Rep 2023;72:1108–14. https://doi.org/10.15585/mmwr.mm7241a2 PMID:37824430

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

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