Monoclonal antibodies for post-exposure prophylaxis could save lives and money

Administering monoclonal antibodies as post-exposure prophylaxis to unvaccinated Americans ages 50 and older with household members with a COVID-19 variant that is susceptible to treatment could save millions of dollars and prevent hundreds of deaths, a new study has shown.

The study of the analytical decision model, published in Open JAMA Network, included 1555 participants in the Regen-Cov PEP trial, of whom 753 received monoclonal antibodies as post-exposure prophylaxis (mAb PEP) and 752 in a placebo group. The REGEN-COV PEP trial tested an antibody combination of casirivimab and imdevimab given to unvaccinated COVID-19 negative participants within 96 hours of a household member testing positive for COVID-19. The decision analytic model also included data on confirmed cases for 154,136 people and vaccination coverage for 1,888 people, as well as data on 1,276,716 households including 3,088,232 people.

“In this simulated U.S. population modeling study, a mAb PEP program for COVID-19 was estimated to improve health outcomes and reduce costs,” said study authors, led by Abraham D. Flaxman, PhD, of the Institute for Health Metrics and Evaluation at the University of Washington, wrote. “In the setting of a susceptible variant of SARS-CoV-2, the health system and public health actors would have the opportunity to improve health and reduce net costs to the payer through PEP COVID- 19 with mAbs.”

The study modeled a month with COVID-19 transmission similar to May 2021, and 50% of exposed, unvaccinated household members aged 50 and older receiving monoclonal antibodies. The model estimated that post-exposure prophylaxis could prevent between 528 and 1404 hospitalizations and between 84 and 223 deaths, depending on the level of transmission.

The estimated cost of COVID-19 hospitalizations due to household exposure was $149 million to $400 million, depending on the rate of transmission. The likelihood of cost savings was highest in people aged 80 years (82% in a low transmission scenario and 100% in a high transmission scenario). For those at the 50-year threshold, there was no probability of cost savings in a low transmission scenario, but the probability of cost savings was 96% in a high transmission scenario.

“Antibody therapies are fast-acting because their off-the-shelf antibodies can immediately bind to the antigen, unlike vaccines that stimulate the body to mount an immune response for weeks,” the study authors wrote. . “This fast-acting protective property makes antibody therapies potentially attractive for use in household exposure situations where unvaccinated household contacts are at high risk of acquiring infection over a short period of time and can be identified quickly. However, antibodies are expensive to produce, making it important to assess their optimal use in health economic analyses.

Monoclonal antibodies could be beneficial in scenarios that include high transmission rates; unvaccinated people; high-risk exposure, such as within households or long-term care facilities; and among those who are immunocompromised and unlikely to mount an immune response to vaccines.

The Food and Drug Administration granted emergency use authorization for Regen-Cov as post-exposure prophylaxis for certain at-risk individuals, but later limit the use antibody treatment with bamlanivimab and etesevimab after research showed it was unlikely to be effective against the Omicron variant of COVID-19.

“Promising progress in efforts to isolate and develop mAbs with activity against a broad spectrum of sarbecoviruses may reduce the risk of loss of activity with future SARS-CoV-2 genotypes/variants,” the authors noted. the study.

A variant-agnostic therapy currently in development is Hunigen’s monoclonal antibody lenzilumab, which has shown promise for treating the hyperinflammatory response to SARS-CoV-2 infection in phase 3 trials. recently published.

The emergence of new variants does not always mean that monoclonal antibodies will be less effective. A recent study showed that monoclonal antibodies more effectively neutralize Omicron’s new BA.2 subvariant than the original BA.1 subvariant.