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Estimated Health Outcomes and Costs of COVID-19 Prophylaxis With Monoclonal Antibodies Among Unvaccinated Household Contacts in the US

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Key Points

Question  What are the potential health outcomes and costs of SARS-CoV-2 monoclonal antibody postexposure prophylaxis (PEP) for household contacts of people with COVID-19 in the US?

Findings  In this decision analytical model study, for a month with transmission intensity similar to that of May 2021, a monoclonal antibody PEP program reaching 50% of exposed, unvaccinated household members aged 50 years and older was estimated to avert 528 hospitalizations and 84 deaths in a low-transmission scenario and 1404 hospitalizations and 223 deaths in a high-transmission scenario. The program was also estimated to be cost saving to payers in the high-transmission scenario as a result of averted hospitalizations.

Meaning  These findings suggest that COVID-19 PEP with monoclonal antibodies may be associated with reduced costs and improved population health.


Importance  The COVID-19 pandemic has led to more than 900 000 deaths in the US and continues to disrupt lives even as effective vaccines are available.

Objective  To estimate the health outcomes and net cost of implementing postexposure prophylaxis (PEP) with monoclonal antibodies (mAbs) against household exposure to COVID-19.

Design, Setting, and Participants  This study is a decision analytical model of results from a randomized clinical trial of casirivimab with imdevimab administered as subcutaneous injections to unvaccinated, SARS-CoV-2–negative household contacts of people with confirmed COVID-19 with complementary data on household demographic structure, vaccine coverage, and confirmed COVID-19 case counts. The study used US data from May 2021 for a simulated population of US individuals of all ages within low-transmission or high-transmission scenarios.

Exposures  Age, sex, race, ethnicity, and COVID-19 vaccination status.

Main Outcome or Measures  Symptomatic infection, hospitalization, death, and net payer cost of monoclonal antibody PEP for COVID-19.

Results  In a month of transmission intensity similar to that of May 2021, a mAb PEP program reaching 50% of exposed, unvaccinated household members aged 50 years and older was estimated to avert 1820 symptomatic infections (95% uncertainty interval [UI], 1220-2454 symptomatic infections), 528 hospitalizations (95% UI, 354-724 hospitalizations), and 84 deaths (95% UI, 55-116 deaths) in a low-transmission scenario and 4834 symptomatic infections (95% UI, 3375-6257 symptomatic infections), 1404 hospitalizations (95% UI, 974-1827 hospitalizations), and 223 deaths (95% UI, 152-299 deaths) in a high-transmission scenario. Without mAb PEP, the estimated cost of hospitalizations due to COVID-19 infections from household exposure in the lower transmission scenario was $149 million (95% UI, $115-$196 million), whereas the estimated hospitalization cost in the higher transmission scenario was $400 million (95% UI, $312-$508 million). In the lower transmission scenario, mAb PEP administered to 50% of eligible contacts aged 80 years and older was estimated to have 82% probability of saving costs, but was not associated with cost savings at age thresholds of 50 years and older or 20 years and older. In contrast, in the high-transmission scenario, mAb PEP administered to 50% of eligible household contacts had estimated cost savings in 100% of simulations at the 80-year age threshold, 96% of simulations at the 50-year threshold, and 2% of simulations at the 20-year thresholds.

Conclusions and Relevance  In this modeling study of a simulated US population, a mAb PEP for COVID-19 program was estimated to improve health outcomes and reduce costs. In the setting of a susceptible variant of SARS-CoV-2, health system and public health actors would have an opportunity to improve health and reduce net payer costs through COVID-19 PEP with mAbs.

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Article Information

Accepted for Publication: March 7, 2022.

Published: April 22, 2022. doi:10.1001/jamanetworkopen.2022.8632

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2022 Flaxman AD et al. JAMA Network Open.

Corresponding Author: Jennifer M. Ross, MD, International Clinical Research Center, Department of Global Health, University of Washington, HMC Box #359927, 325 9th Ave, Seattle, WA 98104 (jross3@uw.edu).

Author Contributions: Dr Flaxman had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Flaxman, Barnabas, Ross.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Flaxman, Issema, Ross.

Critical revision of the manuscript for important intellectual content: Flaxman, Barnabas, Ross.

Statistical analysis: Flaxman, Issema.

Administrative, technical, or material support: Barnabas.

Supervision: Barnabas, Ross.

Conflict of Interest Disclosures: Dr Flaxman reported consulting for Janssen, SwissRe, Merck for Mothers, Sanofi, and Agathos, Ltd. Dr Barnabas reported receiving support from Regeneron Pharmaceutical for writing a conference abstract and a manuscript outside the submitted work. No other disclosures were reported.

Funding/Support: This work was supported by funding from the National Science Foundation (award DMS-1839116).

Role of the Funder/Sponsor: The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

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