COVID-19 Vaccination Reduces Antibiotic Prescription Rates Among Older Adults

Although antibiotics were found to be prescribed regularly among older adults with COVID-19 infection, prior COVID-19 vaccination was associated with reduced prescribing frequency. These study results were published in Clinical Infectious Disease.

This population-wide retrospective study was conducted between January 2020 and December 2021 in Ontario, Canada. Researchers aimed to identify factors associated with antibiotic prescribing following the onset of COVID-19 infection. The study population comprised nursing home residents and community-dwelling older adults. The primary outcomes were the number systemic antibiotics prescribed during the pre- (≤7 days of infection onset) and post-diagnosis (≤7 days after infection onset) periods of COVID-19 infection; both periods comprised the peri-diagnosis period. The rate of antibiotics dispensed per patient between weeks 4 and 8 prior to the index date (control period) were considered baseline prescribing rates. Statistical testing included multivariable regression analysis with generalized linear models.

There were 64,414 patients (age, ≥66 years) included in the final analysis, of whom 13,529 were nursing home residents and 50,885 were community-dwelling older adults. Of the nursing home residents, the mean age was 85 years, 69% were women, and 7% had received at least 2 COVID-19 vaccine doses prior to infection onset. Of the community-dwelling older adults, the mean age was 75 years, 52% were women, and 19% had received at least 2 COVID-19 vaccine doses prior to infection onset.

Among 3022 nursing home residents and 6372 community-dwelling older adults who had at least 1 antibiotic prescription claim during the peri-diagnosis period, 2622 and 5327, respectively, did not have documented obstructive lung disease or positive immunocompromised status.

For nursing home residents, antibiotic prescribing rates were higher in the pre- (15.0 per 1000 person-days [pd]; incidence rate ratio [IRR], 3.5; 95% CI, 3.3-3.8) and post-diagnosis (20.9 per 1000 pd; IRR, 4.9; 95% CI, 4.6-5.3) periods when compared with rates observed in the control period (4.3 per 1000 pd).

Similar findings were observed among community-dwelling older adults, with higher antibiotic prescribing rates noted in the pre- (10.5 per 1000 pd; IRR, 4.1; 95% CI, 3.9-4.3) and post-diagnosis (9.8 per 1000 pd; IRR, 3.8; 95% CI, 3.7-4.0) periods when compared with those observed in the control period (2.5 per 1000 pd).

Factors associated with reduced antibiotic prescribing among nursing home residents in the post-diagnosis period included prior primary series vaccination (IRR, 0.7; 95% CI, 0.4-1) and female sex (IRR, 0.7; 95% CI, 0.7-0.8). However, antibiotic prescribing rates in the post-diagnosis period were increased among nursing home residents with chronic kidney disease (IRR, 1.2; 95% CI, 1.1-1.4) and those with immunocompromised conditions (IRR, 1.3; 95% CI, 1.1-1.5).

Among community-dwelling older adults, prior receipt of primary series vaccination was associated with reduced antibiotic prescribing rates in the post-diagnosis period (IRR, 0.3; 95% CI, 0.3-0.4). Factors associated with increased prescribing rates during this period included asthma (IRR, 1.5; 95% CI, 1.3-1.7) and chronic obstructive lung disease (IRR, 1.8; 95% CI, 1.5-2.1).

Limitations of this study include potentially limited generalizability and the inability to identify patients with asymptomatic vs symptomatic infection. In addition, these findings were observed during the first 2 years of the pandemic and may not reflect the current relationship between vaccination and antibiotic prescribing practices.

According to the researchers, “COVID-19 vaccination appeared to be a significant factor in reducing antibiotic prescribing rates in patients with SARS-CoV-2, and suggests the vaccine may play a role in broader antibiotic stewardship efforts.”

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.