Know the Latest About COVID-19 Monoclonal Antibodies

Rising cases will renew focus on COVID-19 monoclonal antibodies (casirivimab/imdevimab, etc) for treating mild to moderate illness.

Patients. Early data now suggest casirivimab/imdevimab (Regen-COV) reduces mortality in patients HOSPITALIZED due to COVID-19.

But it's not authorized for these patients yet...and the dose showing benefit is over 6 times the current authorized dose.

For now, continue to focus "mab" use on OUTPATIENTS positive for COVID-19 who are 12 years and up...with mild to moderate symptoms for less than 10 days...and at high risk of severe COVID-19 (diabetes, etc).

Products. Rely on casirivimab/imdevimab for now.

Expect limited use of sotrovimab, the most recently authorized mab.

Outcomes with sotrovimab seem similar to other mabs. But sotrovimab costs about $2,100/dose...and so far, the government hasn't purchased it to provide "at no cost" like other mabs for COVID-19.

And keep in mind, bamlanivimab/etesevimab distribution is currently paused...due to reduced Beta and Gamma viral variant susceptibility.

Clarify that casirivimab/imdevimab or sotrovimab seems to retain activity against these variants.

Administration. Ensure your protocols are updated to reflect the latest casirivimab/imdevimab dosing and administration.

Reduce the dose from 1,200 mg/1,200 mg to 600 mg/600 mg. Data show similar efficacy with the lower dose.

And be aware, it can now be given subcutaneously instead of just IV...the other COVID-19 mabs are IV-only.

But save subcutaneous use of casirivimab/imdevimab for cases where IV isn't feasible or would delay treatment.

Authorization for the subcutaneous route is based on a comparable reduction in viral load...not outcomes data. Plus giving it subcutaneously requires 4 injections of 2.5 mL each.

Use our algorithm, "Mabs" for COVID-19, for quick reference. It's updated with details about using casirivimab/imdevimab for post-exposure prophylaxis...its latest authorized use.

See our chart, Treatments of Interest for COVID-19, for more guidance about other meds for inpatient and outpatient use.

Key References

  • medRxiv Published online June 16, 2021; doi:10.1101/2021.06.15.21258542
  • medRxiv Published online May 28, 2021; doi:10.1101/2021.05.27.21257096
  • medRxiv Published online June 6, 2021; doi:10.1101/2021.05.19.21257469
  • (7-30-21)
  • (7-30-21)
Hospital Pharmacist's Letter. August 2021, No. 370822

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