Rapid antigen testing for respiratory syncytial virus (RSV) in primary care may significantly curb unnecessary antibiotic prescribing in young children with lower respiratory tract infections, according to a new cohort study published in JAMA Network Open.1 The findings have direct relevance for pulmonologists concerned with antimicrobial stewardship, diagnostic uncertainty, and the downstream consequences of antibiotic overuse in early life.
RSV remains the leading cause of viral lower respiratory tract infections (VLRTIs) in infants and young children worldwide, frequently manifesting as bronchiolitis or viral pneumonia, according to the report. Despite clear guidance discouraging antibiotic use for uncomplicated viral infections, real-world prescribing remains high, particularly in outpatient and community settings where access to diagnostics is limited and clinicians face pressure to act amid clinical ambiguity.
In the new investigation, lead author Riccardo Boracchini, MSc, of the Laboratory of Healthcare Research and Pharmacoepidemiology at the University of Milan-Bicocca, Milan, Italy, and colleagues analyzed data from the Pedianet network, a large Italian primary care database covering about 4% of the country’s pediatric population. The retrospective cohort study evaluated 256 VLRTI cases among children aged 9 months to 36 months during the 2023 to 2024 RSV season, alongside matched historical and contemporaneous cohorts from the 2022 to 2023 and 2023 to 2024 seasons.
Children in the main cohort underwent point-of-care RSV antigen rapid diagnostic testing (Ag RDT), with cases classified as RSV-positive or RSV-negative. These groups were then compared with children who were not tested who received a purely clinical diagnosis of VLRTI or bronchiolitis. The primary outcome was antibiotic prescribing within 14 days of diagnosis, excluding prescriptions linked to suspected bacterial coinfection or elevated inflammatory markers, according to the study.
Overall, the implementation of RSV Ag RDT was associated with a marked reduction in antibiotic use. Researchers found that among children tested, those with confirmed RSV infection were significantly less likely to receive antibiotics than those who were RSV-negative. Antibiotic prescribing rates were 0.18 prescriptions per 10 person-days in RSV-positive cases compared with 0.29 in RSV-negative cases, corresponding to a 48% relative reduction in risk (RR, .52; 95% CI, .33-.83).
“RSV Ag-RDT may serve as a valuable tool to assist clinicians in distinguishing viral from bacterial etiologies and in guiding more appropriate treatment decisions,” Boracchini said. “This study’s findings underscore the importance of combining RSV prevention strategies, including universal immunoprophylaxis, with Ag-RDT implementation and broader antimicrobial stewardship efforts to enhance prescribing practices.”
When the investigators expanded the comparison to include matched cohorts of clinically diagnosed VLRTIs, testing itself appeared to influence prescribing behavior. Children who underwent RSV testing—regardless of the result—had consistently lower rates of antibiotic prescriptions than children who were not tested and diagnosed on clinical grounds alone. Relative risk reductions were observed in both the 2022 to 2023 season (RR, .54) and the 2023 to 2024 season (RR, .61).
The effect was even more pronounced when focusing exclusively on RSV-confirmed cases, they said. Compared with children given a clinical VLRTI diagnosis without testing, RSV-positive cases had a two-thirds reduction in antibiotic prescribing risk in 2022 to 2023 (RR, .33) and a 59% reduction in 2023 to 2024 (RR, .41).
For pulmonologists, the bronchiolitis subgroup may be particularly salient. Among children younger than 24 months, RSV Ag RDT use was associated with significantly lower antibiotic prescribing compared with clinically diagnosed bronchiolitis in the 2022 to 2023 season (RR, .56). RSV-confirmed bronchiolitis cases showed even stronger reductions (RR, .33).
In the 2023 to 2024 season, however, these differences did not reach statistical significance. The authors suggest that declining baseline antibiotic use over time—likely reflecting the impact of national bronchiolitis guidelines and stewardship campaigns—may have reduced the apparent incremental benefit of testing in more recent seasons.
Importantly, withholding antibiotics in RSV-positive cases did not appear to compromise short-term safety, they noted. Rates of emergency department visits or hospitalization within 14 days were similar between children who were RSV-positive and RSV-negative who did not receive antibiotics, providing reassurance that reduced prescribing was not associated with early clinical deterioration.
Boracchini acknowledged the study’s limitations, including modest sample size, lack of adjustment for disease severity, and reliance on manufacturer-reported test performance. Nonetheless, he said that by leveraging real-world data across multiple seasons and matched cohorts, the study provides some of the strongest evidence to date that RSV Ag RDTs can reduce inappropriate antibiotic use outside the hospital setting.
References
1. Boracchini R, Brigadoi G, Salvadori S, et al. RSV detection and antibiotic prescribing decisions for pediatric respiratory tract infections. JAMA Netw Open. 2026;9(3):e260409. doi:10.1001/jamanetworkopen.2026.0409
