An analysis of outpatient antibiotic prescribing in the United States from 2017 through 2021 shows that rates of inappropriate prescribing returned to baseline levels following a brief dip at the beginning of the COVID-19 pandemic, US researchers reported this week in Clinical Infectious Diseases.

The interrupted time series analysis included more than 37.5 million enrollees in national commercial and Medicare Advantage claims database and looked at prescriptions for antibiotics dispensed to children and adults each month from 2017 through 2020. They used a previously developed antibiotic appropriateness scheme to determine whether diagnostic codes on the medical claims “always,” “sometimes,” or “never” justified antibiotic use.

Among the 60.6 million antibiotics dispensed during the study period, 15.6% were appropriate, 29.4% were potentially appropriate, 25% were inappropriate, and 30% were not associated with a recent diagnostic code.

The proportion of enrollees with one or more inappropriate prescriptions was 1.7% in December 2019. In April 2020, it dipped to 0.9%. But by December 2021, the proportion of enrollees with one or more inappropriate antibiotic prescriptions was back to 1.7.%. Notably, from March 2020 through December 2021, one of the two most common diagnoses among people who received inappropriate antibiotics was “contact with and suspected exposure to COVID-19.”