Monoclonal Antibody Combo Helped Prevent COVID-19 Household Transmission

A new study has found significant benefits from using a monoclonal antibody combination to help prevent COVID-19 transmission to other members of households. The authors point out that the need for “a complementary approach” to prevent the spread of COVID-19 is desperately needed. Here is more information.

PHILADELPHIA – Despite optimism at various points during the pandemic that the end was near, SARS-CoV-2 has not been eradicated, even with the use of highly effective vaccines.

“Moreover, it is unclear how many persons will ultimately choose to become vaccinated, how vaccine efficacy will wane over time, and how great a problem emerging variants of concern will be,” according to a new study in The New England Journal of Medicine. “For these reasons, a need will persist for a complementary approach to prevent the spread of SARS-CoV-2 infection in persons who are not vaccinated, who have waning vaccine-mediated protection over time or because of the emergence of variants, or who are immunocompromised and cannot mount an antibody-mediated antiviral response.”

What might be helpful, advised the researchers from industry, the University of Pennsylvania and other locations, might be greater use of monoclonal antibodies or combinations of them.

This is important information for pharmacists, who recently have been authorized to order and administer monoclonal antibody therapy. Monoclonal antibodies are laboratory-made proteins that mimic the immune system’s ability to fight off harmful pathogens, such as viruses like SARS-CoV-2.

The study pointed out that REGEN-COV -- previously known as REGN-COV2), which is a combination of the monoclonal antibodies casirivimab and imdevimab,-- has been demonstrated to be effective in reducing the risk of hospitalization or death among high-risk persons with coronavirus disease 2019 (COVID-19).

On the other hand, the authors wrote, it is unknown whether subcutaneous REGEN-COV prevents SARS-CoV-2 infection and its spread through household exposure to people at high risk for infection and severe cases.

To determine that, researchers focused on 753 participants 12 and older who were enrolled within 96 hours after a household contact received a diagnosis of SARS-CoV-2 infection. The household contacts without a diagnosis were randomly assigned, in a 1:1 ratio, to receive a total dose of 1,200 mg of REGEN-COV or matching placebo administered through subcutaneous injection. Defined as the primary efficacy endpoint was the development of symptomatic SARS-CoV-2 infection through day 28 in participants who did not have SARS-CoV-2 infection --as measured by reverse-transcriptase–quantitative polymerase-chain-reaction assay -- or previous immunity –seronegativity.

Results indicated that symptomatic SARS-CoV-2 infection developed in 11 of 753 participants in the REGEN-COV group (1.5%) vs.59 of 752 participants in the placebo group (7.8%) (relative risk reduction [1 minus the relative risk], 81.4%; P<0.001).

The authors add that, in weeks 2 to 4, a total of 2 of 753 participants in the REGEN-COV group (0.3%) and 27 of 752 participants in the placebo group (3.6%) had symptomatic SARS-CoV-2 infection (relative risk reduction, 92.6%).

“REGEN-COV also prevented symptomatic and asymptomatic infections overall (relative risk reduction, 66.4%),” they wrote. “Among symptomatic infected participants, the median time to resolution of symptoms was 2 weeks shorter with REGEN-COV than with placebo (1.2 weeks and 3.2 weeks, respectively), and the duration of a high viral load (>10⁴ copies per milliliter) was shorter (0.4 weeks and 1.3 weeks, respectively). No dose-limiting toxic effects of REGEN-COV were noted.”

REGEN-COV, binds noncompeting epitopes of the receptor-binding domain of the SARS-CoV-2 spike protein, according to the study, which adds that the therapy has neutralization potency against circulating SARS-CoV-2 variants of concern, including B.1.1.7 (or alpha), B.1.351 (or beta), B.1.617.2 (or delta), B.1.429 (or epsilon), and P.1 (or gamma), in vitro and in vivo. It also might protect against the selection of resistant variants, they said.

“In outpatients with Covid-19, the use of REGEN-COV has been shown to reduce the incidence of hospitalization or death from any cause by approximately 70%, rapidly reduce the viral load, and shorten the duration of symptoms,” the researchers noted.

The authors explain that, in designing this phase 3 clinical trial, they expected a high background incidence of lateral transmission in households with a documented SARS-CoV-2 patient quarantining alongside other household members. Nothing that the high incidence has subsequently been confirmed, “This scenario is typical of many other scenarios in which uninfected persons are in close proximity to infected persons and would be at high risk for infection. These settings include hospitals, nursing homes, dense housing complexes, prisons, and schools,” they write. “Prevention in these high-risk settings would also correlate with prevention in lower-risk settings.”

The study team states that the data “provide support for the potential use of REGEN-COV to prevent SARS-CoV-2 infection and symptomatic disease in persons in whom immediate protection is warranted; the use of REGEN-COV in such persons could decrease further spread and transmissibility of SARS-CoV-2 infection.”

Licensed pharmacists became authorized to order and administer specific COVID-19 therapeutics, including subcutaneous monoclonal antibodies, as the result of actions in early September by the Department of Health and Human Services. HHS announced an amendment to the COVID-19 Public Readiness and Emergency Preparedness (PREP) Act declaration to allow pharmacists to expand their practices to do that.