COVID-19 vaccination is associated with reduced outpatient antibiotic prescribing in older adults with confirmed SARS-CoV-2: a population wide cohort study

Background — Antibiotics are frequently prescribed unnecessarily in outpatients with COVID-19. We sought to evaluate factors associated with antibiotic prescribing in those with SARS-CoV-2 infection.

Methods — We performed a population-wide cohort study of outpatients 66 years or older with PCR-confirmed SARS-CoV-2 from January 1st 2020 to December 31st 2021 in Ontario, Canada. We determined rates of antibiotic prescribing within 1-week before (pre-diagnosis) and 1-week after (post-diagnosis) reporting of the positive SARS-CoV-2 result, compared to a self-controlled period (baseline). We evaluated predictors of prescribing, including a primary series COVID-19 vaccination, in univariate and multivariable analyses.

Results — We identified 13,529 eligible nursing home residents and 50,885 eligible community dwelling adults with SARS-CoV-2 infection. Of the nursing home and community residents, 3,020 (22%) and 6,372 (13%) received at least one antibiotic prescription within 1 week of a SARS-CoV-2 positive result, respectively. Antibiotic prescribing in nursing home and community residents occurred at 15.0 and 10.5 prescriptions per 1000 person-days pre-diagnosis and 20.9 and 9.8 per 1000 person-days post-diagnosis, higher than the baseline rates of 4.3 and 2.5 prescriptions per 1000 person-days. COVID-19 vaccination was associated with reduced prescribing in nursing home and community residents, with adjusted post-diagnosis IRRs of 0.7 (95%CI 0.4-1) and 0.3 (95%CI 0.3-0.4) respectively.

Conclusions — Antibiotic prescribing was high and with little or no decline following SARS-CoV-2 diagnosis, though was reduced in COVID-19 vaccinated individuals, highlighting the importance of vaccination and antibiotic stewardship in older adults with COVID-19.