Kids with flu often don’t get antiviral drugs, study shows

Rates of influenza antiviral drug prescribing among US children from 2010 to 2019 varied widely and were low in all age-groups, but especially among those younger than 2 years old, according to a study published today in Pediatrics.

The Vanderbilt University–led study included national commercial insurance claims for 1,416,764 antiviral drug prescriptions for children and adolescents seen at outpatient clinics, urgent care, or emergency departments (EDs) within 2 days of symptom onset and those at high risk for flu complications. The antivirals studied were oseltamivir (Tamiflu), baloxavir (Xoflusa), and zanamivir (Relenza); oseltamivir is the only one approved for children younger than 5 years.

The median patient age was 9 years, and boys and older children were most likely to receive an antiviral. Children with risk factors for flu complications made up 63.3% of the study population.

Guideline-concordant dispensing for youngest kids only 37%

Almost all prescriptions (99.8%) were for oseltamivir. The overall prescribing rate was 20.6 per 1,000 children per season (range, 4.35 to 48.6 per 1,000) and rose over the study period. The overall dispensing rate per 1,000 flu diagnoses was 606 (range, 494 to 673 per flu season).

Antiviral dispensing among children with a flu diagnosis and prophylactic (preventive) treatment varied by age, with children aged 12 and older receiving more antiviral treatment and children 2 to 11 years old receiving more prophylactic dispensing.

Antiviral prescribing among flu patients younger than 2 years was 367 per 1,000 diagnoses (prophylactic dispensings, 233 per 1,000). National guideline-concordant antiviral prescribing among children younger than 2 years at high risk for flu complications was 37%.

These findings are especially concerning given that influenza disproportionally affects young children and results in a greater number of clinic visits, emergency department visits, influenza complications, and hospitalizations in children <5 years of age compared with older children and adolescents.

There were wide geographic differences. For example, during the 2018-19 season, there was a threefold differences in antiviral prescribing rates, ranging from 25 per 1,000 in the Pacific region to 78 per 1,000 in the east south central region. The median weighted percentage of visits for influenza-like illness in these regions was 2.48 in the Pacific and 3.39 in the east south central region, a 37% difference.

The total inflation-adjusted cost for antivirals was more than $208 million across all seasons studied (median, $138), and median inflation-adjusted cost ranged from $111 to $151 per course. The 2017-18 season cost the most ($46.3 million), and the 2011-12 season cost the least ($7.8 million).

“These findings are especially concerning given that influenza disproportionally affects young children and results in a greater number of clinic visits, emergency department visits, influenza complications, and hospitalizations in children <5 years of age compared with older children and adolescents,” the study authors wrote.

The Infectious Disease Society of America, US Centers for Disease Control and Prevention (CDC), and the American Academy of Pediatrics recommend that providers consider oseltamivir for children within 48 hours of flu symptom onset and strongly recommend it for those at high risk for complications or household exposure.

“Treatment of children in the outpatient setting has been reported to decrease symptom duration, household transmission, antibiotic use, and influenza- associated complications like ear infections,” lead author James Antoon, MD, PhD, MPH, said in a Vanderbilt news release. 

Antivirals important adjunct to vaccines

In a related commentary, Pia Pannaraj, MD, MPH, of the University of California at San Diego, said some providers and parents may not understand that flu is a serious threat to children.

“Bacterial infections of the upper respiratory tract, such as otitis media and sinusitis, can occur in 20% to 50% of healthy individuals, and complications of the lower tract, including bronchitis and pneumonia, can lead to hospitalizations,” she wrote. “Importantly, it is underrecognized that 50% of pediatric influenza deaths occur in otherwise healthy children.”

Pannaraj called for research into providers’ and parents’ concerns about the use of antivirals in children with flu. “Are there factors related to cost, insurance coverage, knowledge of antiviral options, perception of benefit, antiviral shortages, regional climate, culture, media coverage, and/or social media on clinical practices?” she wrote.

Because the effectiveness of the flu vaccine varies from season to season, and fewer children have received vaccines since the COVID-19 pandemic began, antivirals have an important role in preventing flu complications. “When it comes to influenza, we should be using all the tools in our toolbox,” she concluded.