ELIGIBILITY — In May 2021, the FDA expanded the criteria by which a patient with COVID-19 can be considered at high risk for disease progression. All persons ≥12 years old who are overweight, pregnant, or have cardiovascular disease, hypertension, or chronic respiratory disease are now considered high-risk (see Table 2).4

CLINICAL STUDIES — In an unpublished double-blind trial (BLAZE-2 Part 1; summarized in the FDA Fact Sheet), 966 SARS-CoV-2-negative residents or staff of skilled nursing facilities where a confirmed SARS-CoV-2 infection occurred were randomized to receive a single dose of bamlanivimab 2800 mg (without etesevimab) or placebo.

The risk of symptomatic COVID-19 within 8 weeks of randomization, the primary endpoint, was significantly lower in patients who received bamlanivimab than in those who received placebo in both the overall population (8.5% vs 15.2%; number needed to treat [NNT] 15.1; adjusted OR 0.43 [95% CI 0.28-0.68]) and the prespecified subgroup of nursing facility residents (8.9% vs 22.5%; NNT 7.4; adjusted OR 0.20 [95% CI 0.08-0.49]). There were no deaths due to COVID-19 in the bamlanivimab group versus 4 in the placebo group.2,5

No data on the use of bamlanivimab plus etesevimab for post-exposure prophylaxis of COVID-19 are available. Because the combination has greater antiviral activity than bamlanivimab alone, the FDA presumed it to be effective based on the results of BLAZE-2 Part 1. No clinical trials have compared bamlanivimab plus etesevimab with casirivimab plus imdevimab.

ADVERSE EFFECTS — Infusion-related reactions and anaphylaxis have been reported with use of bamlanivimab plus etesevimab.

VARIANTS — Bamlanivimab plus etesevimab is not active against the Omicron variant of SARS-CoV-2. The combination retains activity against the Delta variant of the virus.2

DOSAGE AND ADMINISTRATION — The authorized dosage of bamlanivimab plus etesevimab for post-exposure prophylaxis is 700 mg of bamlanivimab and 1400 mg of etesevimab given as a single IV infusion as soon as possible after exposure to SARS-CoV-2. Patients should be monitored during the infusion and for at least 1 hour after its completion. Unlike REGEN-COV, bamlanivimab and etesevimab cannot be given by subcutaneous injection. Detailed instructions on preparation and administration of the antibodies are available in the FDA Fact Sheet.2

CONCLUSION — The FDA has authorized administration of the monoclonal antibodies bamlanivimab and etesevimab together for IV post-exposure prophylaxis of COVID-19 in certain high-risk persons. In a double-blind trial in SARS-CoV-2-negative residents and staff of nursing facilities in which a confirmed infection occurred, IV infusion of bamlanivimab alone significantly decreased the risk of symptomatic COVID-19 compared to placebo. The overall effectiveness of the two antibodies together for post-exposure prophylaxis remains to be determined. Bamlanivimab plus etesevimab retains efficacy against the Delta variant of SARS-CoV-2.

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