Outpatient antibiotic prescribing for medically attended respiratory syncytial virus, influenza, or human metapneumovirus illness among high-risk adults in rural Wisconsin, United States

Abstract

Background: Vaccines have an important role in reducing antibiotic prescribing. Population-based estimates of antibiotic prescribing for acute viral respiratory illness among high-risk populations are needed to inform vaccine policy-making. Our objective was to derive population-based estimates of seasonal outpatient antibiotic prescriptions among high-risk adults with respiratory syncytial virus (RSV), influenza, or human metapneumovirus (hMPV) illness.

Methods: We included adults with laboratory-confirmed medically attended RSV, influenza, or hMPV illness and ≥1 high-risk condition enrolled in the US Flu VE Network in central and northern Wisconsin, 2015-16 to 2019-20. We extracted data on outpatient antibiotics prescribed ≤7 days of enrolment. We estimated the seasonal number of antibiotic prescriptions associated with each viral illness per 10 000 high-risk adults using Poisson regression and stratification and weighting. We incorporated adjustment factors to account for incomplete overlap between influenza and RSV or hMPV seasons using state respiratory infection surveillance data.

Results: 3601 respiratory specimens from high-risk adults were included. 303 (8.4%), 1011 (28%), and 289 (8.0%) tested positive for RSV, influenza, or hMPV, respectively. 106/303 (35%), 174/1011 (17%), and 107/289 (37%) patients received ≥1 antibiotic prescription, respectively. After stratification and weighting, seasonal population-based estimates for the number of antibiotic prescriptions where 29 (95% confidence interval 22-39), 52 (41-65), and 31 (24-40) per 10 000 high-risk adults, respectively.

Conclusion: Our results suggest that RSV, influenza, and hMPV illness contribute substantially to antibiotic prescribing among high-risk adults in rural Wisconsin. Understanding the impact of vaccines on antibiotic use and resistance is imperative for assessing their full public health value.