A Real-World Cohort Study of Bamlanivimab Versus Bamlanivimab-Etesevimab for Non-severe COVID-19

ABSTRACT

Background. Anti-spike monoclonal antibodies (mAb) including Bamlanivimab (BAM) and Bamlanivimab-Etesevimab (BAM/E) have shown reduced hospitalization rates for non-severe coronavirus disease 2019 (COVID-19) in clinical trials. Recent studies provided real-world hospitalization rates for BAM. But, similar data on those who received BAM/E are lacking. In spring 2021, Michigan experienced a surge of COVID-19 with more cases per capita than any other state. We sought to quantify the impact of BAM monotherapy versus BAM/E combination on hospitalization and mortality among a real-world high-risk cohort of outpatients with COVID-19. Methods. This retrospective cohort study evaluated outpatients ≥18 years with laboratory-confirmed mild/moderate COVID-19 who received mAb in a Detroit health system based on emergency use authorization criteria. Inclusion began on December 3rd 2020 with BAM monotherapy, changed to BAM/E combination on March 27, 2021, and included patients until April 19th 2021 (Figure 1). Demographics, comorbidities, and clinical characteristics were compared between patients who received BAM verses BAM/E using Chi-square and Mann-Whitney U test. Primary outcome was 30-day COVID-19 related hospitalization. Secondary outcomes were 30-day mortality and length of stay (LOS). Inclusion began on December 3rd 2020 with BAM monotherapy, changed to BAM/E combination on March 27, 2021, and included patients until April 19th 2021. In spring 2021, Michigan experienced a surge of COVID-19 with more cases per capita than any other state resulting in a large sample of real-world patients for analysis. Results. 643 patients received mAb (294 in BAM group and 349 in BAM/E group). Patients in the BAM/E cohort were younger and more obese with lower rates of diabetes, myocardial infarction, and cancer. Other characteristics were similar (Table 1). BAM/E patients had longer time from symptom onset to infusion (6 vs 4 days, p< 0.001). COVID-19 related 30-day hospitalization rates did not differ between groups (7.8 vs 7.2%, p=0.751). LOS and 30-day mortality (1% vs 0.3%, p=0.238) were also similar (Table 2). Patients in the BAM/E cohort were younger and more obese with lower rates of diabetes, myocardial infarction, and cancer. Other characteristics were similar BAM/E patients had longer time from symptom onset to infusion (6 vs 4 days, p<0.001). COVID-19 related 30-day hospitalization rates did not differ between groups. Length of stay and 30-day mortality were also similar. Conclusion. Rates of hospitalization in our study were higher than in clinical trials of mAB and may reflect differences in study populations (Table 3). Compared to other real-world studies, our cohort of young, obese, and Black patients, had similar hospitalization rates of 7.5%. The lack of difference in outcomes noted among the mAB formulations in our study may be related to longer time from symptom onset to infusion in the BAM/E combination group. Our patients were older with higher rates of obesity and other comorbidities than those in clinical trials (shown in orange). Compared to other real-world studies (in blue), our cohort of younger, more obese Black patients had similar hospitalization rates of 7.5%.