Subcutaneous REGEN-COV Antibody Combination to Prevent Covid-19
Creators: name: Isa, F.
name: Herman, G.
name: Hou, P.
name: Bar, K.J.
name: Chan, K.-C.
name: Braunstein, N.
name: Hurt, C.B.
name: Purcell, L.A.
name: Perez-Perez, R.
name: Turner, K.C.
name: Kim, Y.
name: Heirman, I.
name: Hamilton, J.D.
name: Forleo-Neto, E.
name: Lipsich, L.
name: Cohen, M.S.
name: Hooper, A.T.
name: the Covid-19 Phase 3 Prevention Trial Team
name: Sarkar, N.
name: Yancopoulos, G.D.
name: Baum, A.
name: Barouch, D.H.
name: Mohseni, R.
name: O'Brien, M.P.
name: Krainson, J.
name: DiCioccio, A.T.
name: Kyratsous, C.A.
name: Mahmood, A.
name: Ramesh, D.
name: Barnabas, R.V.
name: Davis, J.D.
name: Marovich, M.A.
name: Musser, B.J.
name: Weinreich, D.M.
name: Stahl, N.
name: Burwen, D.R.
name: Kowal, B.
Publisher: name: Massachussetts Medical Society
Year: 2021

description: BACKGROUND REGEN-COV (previously known as REGN-COV2), a combination of the monoclonal antibodies casirivimab and imdevimab, has been shown to markedly reduce the risk of hospitalization or death among high-risk persons with coronavirus disease 2019 (Covid-19). Whether subcutaneous REGEN-COV prevents severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and subsequent Covid-19 in persons at high risk for infection because of household exposure to a person with SARS-CoV-2 infection is unknown. METHODS We randomly assigned, in a 1:1 ratio, participants (=12 years of age) who were enrolled within 96 hours after a household contact received a diagnosis of SARSCoV- 2 infection to receive a total dose of 1200 mg of REGEN-COV or matching placebo administered by means of subcutaneous injection. At the time of randomization, participants were stratified according to the results of the local diagnostic assay for SARS-CoV-2 and according to age. The primary efficacy end point 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 Symptomatic SARS-CoV-2 infection developed in 11 of 753 participants in the REGEN-COV group (1.5%) and in 59 of 752 participants in the placebo group (7.8%) (relative risk reduction [1 minus the relative risk], 81.4%; P<0.001). 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%). 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. CONCLUSIONS Subcutaneous REGEN-COV prevented symptomatic Covid-19 and asymptomatic SARS-CoV-2 infection in previously uninfected household contacts of infected persons. Among the participants who became infected, REGEN-COV reduced the duration of symptomatic disease and the duration of a high viral load.